She swears, she drinks, she has extramarital flings… The modern MP’s wife is unrecognisable from the simpering cheerleader of the past. So what has changed? And what impact will the other halves have on this year’s election?

When Alicia Collinson’s husband, Damian Green, was first elected as a Conservative MP in 1997, she was provided with a small pamphlet produced by the Parliamentary Christian Wives Fellowship. It was called “Two for the Price of One” and the title was printed across the cover in precisely the same shade of green as the leather benches inside the House of Commons chamber. The eight-page leaflet contained all manner of helpful tips and guidance on how to be a politician’s wife in a breezy style that seemed to have come straight from the 1950s.

“If you look good, you feel good,” the authors stated cheerily, before going on to advise that: “For wives, it is a great help to have a very good relationship with your local garage as you are bound to break down when your dearly beloved is on a parliamentary trip to China and you may need rescuing.”

But it was one sentence in particular that enraged Alicia Collinson. “It’s this one,” she says, pushing the pamphlet across the coffee table and jabbing at the relevant page. “They say: ‘Try to ensure the absent parent speaks each week on the phone to each child personally if possible.’” Collinson snorts with indignation. “That really got my goat. It’s full of things like that, assuming you can do things while your husband’s in parliament. Well, no, you can’t if you’re working, too. There was this assumption that you were just part of the package.”

Times have changed dramatically for the political wife. In previous decades an MP’s wife was expected to be little more than a photogenic adjunct to her husband, someone who could be relied upon to judge cake-baking contests at the village fete and smile prettily in public. Most of the time this charming little creature would be careful not to speak out of turn or proffer any political opinion that might risk embarrassing her husband or his party. Her role, like that of Clementine Churchill or Clarissa Eden before her, was to raise children, run a household and provide constant support to her overworked and sporadically bad-tempered spouse.

On the rare occasion that a wife did speak out, it resulted in a horrified outcry. Margot, the wife of former prime minister Herbert Asquith, was blamed for her husband’s political downfall after she publicly accused her stepson of being drunk. (He had, in fact, been shell-shocked during the First World War.) Now, however, Margot Asquith’s indelicate comment would barely merit a raised eyebrow. In modern politics, it is quite normal for the wife of the chancellor to scream the “c” word in reference to her husband’s treacherous colleagues, as Maggie Darling was reported to have done in Andrew Rawnsley’s recent book about the fall of New Labour. Over the past few months a worrying number of political wives (and it is, on the whole, still largely wives rather than husbands) have crawled out of the woodwork to admit to all sorts of brazen peccadilloes, including binge drinking, promiscuity and the odd extramarital affair.

Sally Bercow, the wife of the Commons speaker, gave an extraordinary interview last December in which she admitted to a debauched past, drinking more than two bottles of wine a day and engaging in a string of one-night stands. “I would end up sometimes at a bar and someone would send a drink over, and I’d think: ‘Why not?’ and we’d go home together,” she said. “I liked the excitement of not knowing how a night was going to end.”

Unlike the quietly spoken, loyal wife of parliamentary legend, Mrs Bercow appeared to be wholly unconcerned as to whether she might be diminishing her husband’s professional kudos. Her political opinions, too, are unashamedly opposed to her spouse’s: whereas John Bercow was a Tory MP before becoming speaker, Sally Bercow is standing as a Labour councillor in Pimlico, central London.

Then, in January, it emerged that Iris Robinson, the wife of the Northern Irish first minister, had an affair with a 19-year-old when she was 58. The ensuing barrage of “Mrs Robinson”-themed newspaper headlines forced Peter Robinson to stand down temporarily. Although both the Robinson and Bercow sagas are extreme examples, there is a growing trend for parliamentary spouses to emerge from the shadows.

Samantha Cameron, wife of the Conservative leader, is creative director at Smythson, the luxury stationery firm. Ed Miliband’s partner, Justine Thornton, is a senior environmental lawyer. Sarah Brown, wife of the prime minister, enjoyed a successful career in public relations before taking up permanent residence in No 10. Shadow chancellor George Osborne’s wife, Frances, is a bestselling biographer, and Sandra Howard, wife of former Conservative leader Michael Howard, has written three novels.

“I think the role has changed a bit,” says Mrs Howard, whose latest novel, A Matter of Loyalty, was published last year. “Three decades ago there were more wives who didn’t have their own career. Cherie Blair did us a really good service by continuing to work as a barrister while her husband was the prime minister because no one could ever complain about a spouse working again.”

“It’s a shift that mirrors what has happened in society,” agrees Alicia Collinson, author of Politics for Partners: How to Live with a Politician and a barrister specialising in family law. She deliberately chose not to take her husband’s surname. “I got very criticised in the press when Damian first became involved in politics because I was a barrister and had my own job, but now the constituency isn’t fussed about it… I used to know one MP who talked about his wife being ‘the hostage’ in the constituency.” Collinson takes a sip of her tea. “He’s now married to someone else.”

Not only are political wives no longer quite held hostage in the shires, they are seen as potential vote-winners. The impact of Michelle Obama, who has expanded the role of political wife and is seen as a crucial asset to her husband’s success, is beginning to make itself felt in the UK. Whereas in the past an MP’s spouse was occasionally wheeled out by central office for a pre-election photo opportunity, the modern political wife has a far more complex role. She must juggle the demands of career and family while developing a public persona that is sufficiently straightforward to be inoffensive and yet interesting enough to intrigue the electorate. Her clothes will be scrutinised and her past raked over. She is expected to have an opinion and yet to keep it to herself. And when her husband films a YouTube broadcast from his bespoke Notting Hill kitchen, she must appear in the background amid the cereal boxes and Blu-Tacked toddlers’ paintings, busy and yet in control: the perfect appeal to the Mumsnet generation.

Perhaps it is unsurprising that some political wives, like Sally Bercow or Iris Robinson, chafe against the restrictions imposed upon them. Others, like Miriam González Durántez, wife of the Liberal Democrat leader Nick Clegg, take a more relaxed approach. González, who heads up the trade department of the international law firm DLA Piper, says that a political wife can be “supportive without being submissive… I am sufficiently confident to understand I can have a proper career, and I also understand I happen to be married to Nick and people will want legitimately to have a look into who he is as a person – and provided that they respect our children I’m happy for anybody to have a look. What you see is what you get.”

When we meet in a boardroom at her company headquarters in London, González seeps unapologetic glamour. She has film-star looks and hair that appears expensively blow-dried. Today she is wearing a grey silk shift dress, a chunky gold necklace and fashionable high-heeled ankle boots. It would be difficult to imagine anyone less like the pink-cheeked, floral-swathed MP’s wife of popular imagination.

González embodies the new breed of “Sam Cams”, the independent career women and mothers who happen to be married to politicians but who are determined not to be defined by their spouses and who share the running of the household as equally as possible. The Cleggs have three sons under the age of eight: their father takes them to school every morning and their mother puts them to bed at night.

“Nick’s well known with the neighbours for going to do a very early interview and coming back to go to school before going to Westminster,” says González. Do the children understand what their father does? “Partly. My five-year-old thinks he’s the captain of the Liberal Democrats. My eight-year-old is quite perceptive and understands some of it – he advises on plans to capture Osama bin Laden.”

Westminster hours, however, remain extremely inconvenient for MPs with young children (even since Labour’s landslide victory in 1997, when 120 of the new MPs were women, many of whom were appalled by the unsociable working hours and pitifully outdated office equipment). “It isn’t friendly for families,” says González. “I remember, for example, being very, very shocked – and let’s put this into context: it must be a Westminster village reaction – but I remember Nick saying at some point: ‘I’m a father before being a politician’, and some colleagues were actually thinking: ‘What a weird thing to say.’ I was thinking: ‘Surely that is a perfectly normal thing to say?’ I think it’s incredibly unuseful that Westminster tends to vote at 10 in the evening rather than at four in the afternoon, like you would do in any other kind of job. There’s a lot of evening engagements and media engagements, and that takes a toll on the family.”

It is perhaps partly for this reason that some wives still choose to stay quietly behind the scenes, determinedly ignoring the onward march of equal opportunities. For every Miriam González there is a “Surrendered Wife” like Norma Major, who stood smiling and faithful beside her husband without uttering a single controversial word in public throughout his premiership and who remained loyal to him even after it emerged that he’d had an affair with Edwina Currie. Pauline Prescott, who stood by husband John despite a dalliance with his secretary, calls herself one of a “dying breed” in her autobiography, and is dismissive of “women’s libbers”.

Sandra Howard, who did not publish her first book until her husband had stood down as leader, says the old-style political wife works on the principle that “anything you can do to help, you do. If allowing the person you love to do what they want to do means a little bit of not thinking about what you want to do, it’s almost a non-question.”

The Surrendered Wife must bite her tongue when asked for her opinion, lest she run the risk of embarrassing her husband. “I remember being told that a political spouse will never win the seat for their partner, but they can sure as hell lose it,” says Howard.

When the expenses scandal broke last year, it emerged that almost 80 MPs employed either their wives or girlfriends as parliamentary assistants, secretaries or case workers. (Political husbands are still very much the exception to the rule: Caroline Flint, the Labour MP for Don Valley, employs her husband Phil Cole to run her constituency office, while Margaret Beckett’s spouse, Leo, has been her parliamentary assistant for years.) At the time, there was an outcry at the thought of family members cashing in courtesy of the taxpayer, and the rules governing the employment of spouses and family members are currently under review. The constituency wives, many of whom had worked extremely hard for their MP husbands, felt they had been unfairly scapegoated. Alicia Collinson recalls a trip to the local garden centre with her husband at the height of the expenses scandal to buy some plants. “A man driving his car wound down his window and shouted out: ‘I hope you’ve got a receipt for that,’ and then drove off thinking he was very clever. We’ve never claimed for gardening. It was just ignorant.

“The climate has changed. The respect that parliamentarians were held in is no more… the level of contempt one experiences is quite extraordinary. It’s been very unpleasant. A lot of spouses have been very upset.”

Another wife, who has run her husband’s constituency office for the last 17 years, says: “I got very badly bruised by the whole thing. People don’t realise how hard we work or the hours we put in. We’re the ones who are there at seven in the morning or 11 at night when the phone goes.”

It is perhaps these wives – the uncomplaining troopers who keep their husbands’ schedules organised and their stationery cupboards stocked with Post-it notes – who provide the bridge between the surrendered spouses of the past and the sleekly independent career women of modern times.

But although the increasing number of MPs’ wives pursuing their own careers has been heralded as some sort of feminist breakthrough, much of the media coverage of these women remains distinctly sexist. There is a lingering sense, in spite of the enormous strides made by women such as Cherie Booth and Miriam González, that a political wife’s role is to gaze adoringly at her husband as he makes a keynote speech or to be photographed walking along the Brighton seafront during party conference season, appearing well dressed but not too glamorous in case she is accused of being out of touch with the common man (or woman).

So it is that Sarah Brown – doubtless influenced by the intimate confessions of her Michelle Obama about the president’s bad morning breath – has twice taken to the podium to introduce her husband to the Labour party conference. In 2008 she smiled ingratiatingly and called him “my hero”. Last year she exclusively revealed that Gordon was “not a saint – he’s messy, he’s noisy, he gets up at a terrible hour”.

Mrs Brown, who gave up a career in PR, has carved out a niche as an electoral accessory whose job it is to show Gordon in a warmer, more modern light. One minute Mrs Brown will be in a TV studio, eyes welling up as she listens to her husband unburden his soul to Piers Morgan, the next she will be opening London Fashion Week wearing an Erdem dress and updating her Twitter account (1,118,558 followers and counting, including Paris Hilton and Naomi Campbell).

Sarah Brown has provided us with a whole new category of political spouse: a wife who knows how to exploit modern media in order to promote herself and her husband as a successful brand. She is known to have used her sartorial influence to overhaul her husband’s wardrobe and her PR savvy to insist that the couple went on holiday in Southwold, Suffolk last year in an effort to prove their fondness for England. In fact, so successful has she been in modelling herself as cheerleader-in-chief that one member of the prime minister’s inner circle is said to have dubbed her “Mrs Goebbels”.

As the general election approaches, the leaders’ wives in particular will have a prominent role to play in wooing the voters. Already there have been snide comments emanating from government sources that Samantha Cameron does less charity work than her counterpart in No 10. And at the recent Tory spring conference it felt as though far more attention was paid to the cut of Mrs Cameron’s silk ruffled blouse than to what her husband had to say about fixing “broken Britain”.

“I think the trouble with politicians is they have a fixed image in the media which doesn’t involve their personality,” says Alicia Collinson. “So having another side to both David Cameron and Gordon Brown and allowing their wives to convey something that isn’t just the stiff upper lip of a politician can be helpful for the electorate in the run-up to an election. They can see what a politician is like from every angle.”

But reactions to Sarah Brown’s celebrity among the other political wives are mixed. Some find her acting the part of adoring spouse on the national stage a touch retrograde. Miriam González says she’d always go to see Nick deliver a major speech and would expect him to do the same, but adds that: “I wouldn’t ask him to come to the podium to kiss me afterwards, and that is not what I’d do in reverse.” Others, like Alicia Collinson, believe that having a loyal wife in the public eye “suggests that the politician has at least got good taste”.

And perhaps in the end it is not a wholly irrational reason to vote for a particular MP. They might lie about tax rises, cheat on their expenses and have terrible breath in the morning, but at least they have the love of a good woman who knows how to make friends with Paris Hilton on Twitter.