Or is it all smoothed over with small talk? BBC News Online's Jane Harbidge investigates.

Labour MP Emmanuel Shinwell nearly came to blows with Conservative MP Cyril Osborne as a discussion blew up into a furious row behind the Speaker's chair.

Mr Shinwell was restrained by the intervention of other MPs, but the hostile encounter in the 1960s is not one that has been regularly repeated since.

But it is no secret in Westminster that no love was lost between former prime minister Edward Heath and Harold Wilson, nor between Sir Edward and his successor Lady Thatcher - discernible in the frostiness when they came face-to-face.

And as prime minister Mrs Thatcher was known for her lack of small talk, even with her own ministers.

John Major is popular with both Tory and opposition MPs

The approach of more recent leaders has become more sophisticated: John Major, Tony Blair and William Hague are all widely considered "jolly nice fellows" who would never display any animosity when the "real" person is on show.

Labour MP Paul Flynn recalls how once he was missed off the guest list at an event during a visit by John Major. When the then prime minister arrived, he wanted to know where the local MP was. "And we then sat chatting about the result of a Chelsea football match," says Mr Flynn.

Raising their guard

The answer to the question of inter-relations, it seems, depends on the MPs involved, their mood at the time, their self-restraint - and how genuinely they feel about the issue at stake.

Canny MPs know there are journalists everywhere in Westminster and take care to remain on their guard - even when away from the glare of the Commons cameras.

It just would not do for any disagreements to surface, for they would undoubtedly be reported.

As former Tory MP turned political columnist Jerry Hayes puts it: "Major and Blair would have to put on an act of getting on in the lobby, although in reality I think they did have a grudging respect for each other."

Francis Maude may harbour a secret respect for Gordon Brown

By the same token, Chancellor Gordon Brown and his shadow Francis Maude, who have been seen savaging one another on the floor of the House, no doubt also have a reluctant regard for one another, says Mr Hayes. The reason being that the bright mind of each has met its match.

Liberal Democrat Welsh affairs spokesman Richard Livsey says: "It all depends on the personalities of the ministers and MPs involved. Very jovial people laugh it off.

"It also depends how serious the issue is. If it threatens to split the party, people do feel very strongly and people become cautious about communicating and you see the odd glare.

"But we haven't reached that state really in this parliament - it's not as bad as when Mrs Thatcher left office."

In everyday proceedings, MPs with legal backgrounds are used to fighting it out furiously in the House, as in court, then sharing a drink afterwards.

Former Conservative minister Virginia Bottomley admits: "I find that more difficult since I'm something of a conviction politician and I profoundly believe in things I argue for.

The lobby talk may be polite - but some MPs make one another bristle

"It's thought to be bad form to continue an emotional debate about something away from the Commons but from time to time it does happen. It's rare, but if someone feels strongly about something, they might have a go at a minister."

Shadow Health Secretary Ann Widdecombe, a formidable opponent for anyone on the Labour side, is often seen vitriolically condemning Health Secretary Frank Dobson over the NHS.

But she says there is no question of continuing the scrap if she bumps into him in the corridor.

"Life would be unbearable if people weren't reasonable outside the Chamber," she says.

"There's a huge amount of friendliness between opponents. I would say, 'Hello and what are you doing for Christmas?'"

Best of enemies

She says the dispute would have to be "very big and personal" for an encounter to be hostile.

But no-one would deny that sometimes MPs get under one another's skin.

"Every so often people fall out because there are over 600 people in the House - it's like a big boarding school in that respect, so inevitably there are some clashes of personality, as well as some friendships," says Miss Widdecombe.

But mixing with the enemy has its limits as party plans must be protected, she says.

Frank Dobson: an amiable opponent for Ann Widdecombe

The casual observer of Commons proceedings would not be surprised to learn that Mr Dobson would be terribly amiable coming face-to-face with Miss Widdecombe, even if she has just given him a lashing over NHS waiting lists.

More surprising may be that shadow trade secretary John Redwood - whose caustic Commons attacks would have left a weaker woman than Margaret Beckett in tears - is just as likely to show a pleasant side outside the Chamber.

John Redwood can be relied on for a bitter Commons attack

Labour MP Ann Clwyd says: "There's no hard-and-fast rule. If you've had a disagreement with someone you might want to say, 'You silly idiot, you've got it wrong,' but people move fast in this place and after a sharp exchange, you move on. You don't stand about having long conversations."

Much of the political gossip goes on in the Commons tearoom, dining room, smoking room and bar, where MPs from separate parties sit apart, as much out of tribal convention as political animosity.

But there is less socialising now than in the days of late-night sittings. With more women MPs than ever, members tend to retreat more quickly to their offices or back to their families at the end of business.

John Prescott takes Commons spats seriously, say insiders

For all the back-slapping and goodwill, there are certain senior figures, such as Deputy Prime Minister John Prescott and Tory deputy leader Peter Lilley, suspected by some observers of taking the Commons exchanges all a little too seriously.

"I doubt whether they've spoken more than eight times since 1983," says Mr Hayes.

Mrs Bottomley says greater tensions are to be found outside the Chamber between MPs of the same party who have criticised one another in public.

"I doubt whether Ron Davies and Tony Blair would have had much to say to one another recently," she says.

And Mr Livsey remembers: "There was a huge fall-out from Geoffrey Howe's speech and Michael Heseltine certainly wasn't flavour of the month. I was amazed by the number of Conservative MPs who said they hated Mr Heseltine. I hadn't realised until that point - I knew there were tensions - how much actual hatred there was."

Mrs Bottomley adds: "But the overall atmosphere is of cameraderie. I go out of my way to be friendly to new MPs of any party. We're all Members of Parliament and that's a privilege.

"When I was first a member, I remember Tony Benn giving me advice on sitting in the same place to catch the Speaker's eye."

It's not unusual for opposing MPs to help one another out.

Jerry Hayes recalls: "A few years ago, I was doing an interview on local government with Jamie Cann (Ipswich Labour MP). I told him I knew nothing about the subject, so he briefed me on what arguments I ought to put back to him."

Stage show

Does all this goodwill make a mockery of the ostensibly genuinely-held views so heatedly debated in public?

"It's all an act," says Paul Flynn candidly. "How many actors carry on playing Julius Caesar once they're off stage? People do the ritual scrapping inside, but having got it out of your system no-one wants to continue fighting.

"But socialising with the opposition is regarded as undignified - you just don't see Labour and Tory MPs getting together.

"Having said that, the importance of friends in the Commons shouldn't be overlooked. I have a great admiration for Alan Duncan, for instance.

"And the pairing system often develops into real friendships especially where there are common interests or on visits abroad where you're the only ones who speak English."

Ken Livingstone, on the other hand, refuses to become drawn into debates beyond the floor of the House.