It's 6pm on a Tuesday evening at Portcullis House, the spanking modern annexe to the House of Commons where the nation's elected representatives can meet their querulous constituents or gather in lowing herds of committees. On the first floor, between a portrait of Baroness Thatcher that could freeze your blood at 30 paces and another of a smiling Lord Home of the Hirsel, something is afoot in the modest portals of Meeting Room P.
One by one, 30 politicians in the Westminster uniform of charcoal suits (male) and boxy jackets accessorised with chunky jewellery (female) enter the room, exchange badinage with the ladies at the desk, remove their jackets and shoes and get themselves weighed. The difference between their avoirdupois readings this week and the week before is solemnly recorded by the ladies and, if it shows any downward tendency, it's the signal for delight and a polite, politician's version of punching the air. The MPs pause outside for a little chat, although they represent all three major parties and are, technically, hated professional rivals. They're drawn to this neutral strip of civil-service carpeting by a shared fascination for three things: losing weight, becoming more healthy and talking about it.
They are members of the All-Party Parliamentary WeightWatchers Group, a loose association of health-conscious legislators currently competing to see who can shed more pounds fastest. Unlike former alcoholics they do not have structured meetings, but it's clear they get a buzz from the weekly weigh-in and the conversations that go on in the corridor. If you ever wish to get an MP down from the dizzying eyrie of power in order to discuss mundane matters, get him on to the subjects of food and self-image.
"Anyone will tell you that the MP's lifestyle means you'll gain at least two pounds a year," says Peter Luff, (Con, MP for Mid-Worcestershire). "You sit on endless committees [he is chairman of the Trade and Industry Select Committee], you're wined and dined, and you probably do less activity than before. The only exercise you get is bobbing up and down trying to catch the Speaker's eye." He got into WeightWatchers after receiving a horrible shock. "About two years ago, I saw a photograph of me in a wetsuit taken after I'd learned to dive. I thought the wetsuit held the weight in - but it revealed it in all its glory. So I started eating much less, taking exercise, and I lost nearly two stone over a nine-month period. But I keep in touch with WeightWatchers. I get weighed once a week. A couple of pounds went on at Christmas so it's time to get careful again."
Luff has a weakness. According to the WeightWatchers points system (in which every food or drink has a negative value, and the day's total intake is supposed not to exceed a certain number), Indian takeaways are right off the scale. But Luff is a fan. "It's a terrible thing, the impossibility of having an Indian meal," he sighs. "I was chairman of the Conservative Party's Friends of India. I'm a leading light in Indo-British relations. In fact I'm going to India with a select committee the month after next, and dreading what it'll do to my waistline."
Help is at hand, however. "Don't worry," cries Jane Kennedy (Lab, MP for Liverpool Wavertree). "You can have the tandoori dishes without the curry sauce, but with the yoghurt raita." Ms Kennedy, a sparkling-eyed charmer in a red jacket and silver earrings, turns out to be a Minister of State at the Department of Health, and the past incumbent of some grim jobs.
"I spent three years as security minister in Northern Ireland, and one of the things they joke about is that everybody who goes to Ulster, irrespective of who they are, puts on a stone. They call it the Stormont Stone. You're so looked after, and you're limited in the amount of the exercise you can take." (This is politician speak for: "You're not supposed to show your face outdoors.") But when I came back, I spent a year as the Minister of State for Work and didn't do much about my health. Then you find you can't get into the dress sizes you want to. You start to feel pains in your knees when going up and down stairs. You start to think: 'I'm looking dreadful in photographs' and you conclude it's time to do something about it. So I started WeightWatchers in June last year and by September, I'd lost half a stone. I was so pleased that I kept it up during the summer."
Arrivals at the weigh-in are greeted by the double act of Caroline Cawston and Hannah Slade, the overseer and leader of the Westminster WeightWatchers operation. The former is a large, no-nonsense lady of matronly demeanour, a WW veteran who used to work for a Liberal MP in the 1970s. If a design team were briefed to construct a living embodiment of the British nanny, they would come up with Ms Cawston. You can see her male charges quaking before her disapproval.
"Possibly because I'm slightly older, they pay attention to me," she says. Is she a bit like a whip? "Yes, I like that. I'm the WeightWatchers whip." Perhaps that's why some of them sound like naughty boys. Like Bob Russell (Lib Dem, MP for Colchester), a boyish 59-year-old with a fringe of brushed-forward silver hair. "I keep telling people, it's not how much I've taken off, it's how much I haven't put on," he says. "It's a stabilising thing." He insists that his bad habits are behind him but, somehow, you don't believe a word of it: "I only have one fried breakfast a week. My consumption of fresh fruit and vegetables has gone up. I only have chips once a week." His eyes light up. "Which may well be tonight. Mmmm... [Mr Russell briefly turns into Homer Simpson]...pie and chips..."
"If they're having trouble," says Caroline, "we talk through how they might make small changes, nothing they can't cope with. We give them lots of encouragement, and everybody who comes is very supportive. They know now hard it is to keep going in this place, surrounded by temptations."
The Parliamentary WeightWatchers Group launched an incentive scheme last October - a modest prize of £1,000 to go to the favourite charity of the MP who loses the most weight by 21 March. You'd think the debaters on the green benches had enough on their plates without competitive starvation, tut some of them are seriously keen.
Streets ahead is Sarah McCarthy-Fry (Labour, MP for Portsmouth North), one of the new intake of MPs in May last year. Since she took the WW shilling in mid-October, she's lost 25 pounds, a vertiginous crash-diet that, in anyone but an MP, would suggest a headlong dive into anorexia nervosa. Her motivation was simple: "I gave up smoking three years ago, and put on a good two-and-a-half stone -even size-16 dresses started to get tight. I'm MP for Portsmouth, and when I'm up here on Monday, Tuesday and Wednesday nights, I don't cook. But we eat a lot of dairy products, and a lot of Westminster cream teas in the Pugin Rooms. And you get invited to dinners and receptions: I go to dinner with travel organisations, union officials, constituents. This week I had lunch with the Bishop of Portsmouth. All these things mount up." Ms McCarthy-Fry's keenness is, she says, down to her being "new" - a Commons virgin with a lot of people to connect with.
Pity the lot of the modern MP, chained to an unending round of parties and drinks receptions. But really, it is no joke, finding things to do before a 10pm vote, killing time before going home to your lonesome Kennington pied-à-terre. "I can resist everything but temptation," sighs Lorely Burt (Lib Dem, MP for Solihull), a tempestuous blonde in a satin jacket and leopard-skin top. "And frankly you could become like a whale, ingesting glasses of wine and canapés from morning till night."
Ms Burt, a party whip, has tried every slimming treatment from Slendertone electric-shock therapy to a mechanical sit-up device. Sandra Gidley (Lib Dem, MP for Romsey) says that, at Westminster: "You're not in control of your destiny." A specialist in serious health issues, she marvels at the way you can attend a reception given by a cancer organisation, "and they gave us big cakes to eat, and doughnuts. I thought, since this is about cancer, shouldn't they have some fresh fruit or something?" In the Commons canteen, she says, there's a salad bar, "but it has lots of dressings and it's not clear which ones are good for you." And in the tea room, "it's lots of things with toast and butter. You could have a salad - but you see someone tucking into a steak sandwich and it's hard to resist."
Many of the MPs currently signed to the weight-loss programme talk at length about fat being a political issue - not one that requires legal action (like banning smoking) or subsidy (like improving school dinners), but one that recognises a nationwide discontent about being overweight.
"I'm not happy with my image," says Jane Kennedy, "and I know lots of people in my constituency who share my concern - it's not about obesity, more a kind of upsetness that you're not healthier, that you can't play football with your grandchildren, that you're not sleeping properly."
Many of the group feel they are offering an example to others - but for the moment, perhaps, mostly to the Nicholas Soameses in the Commons canteen. "It's terribly simple," said Ms Kennedy. "Change what you eat, take a bit of exercise and you've cracked it. How hard is that? To those ministers who say to me, 'I don't have time to do all this - my diary wouldn't permit it,' I say, 'Change your diary.'"Reuse content