This year, my wife Mary and I will host our last champagne and shepherd’s pie party at our London penthouse overlooking the Thames.

I’m sad, of course, but after 40 years we’re calling time on this Christmas institution because, frankly the guests — quite a lot of them old fogeys like me — are finding it increasingly hard to stand for two-and-a-half hours.

I’m 83 and I’m quite exhausted after hosting 200 or so guests a night. We always have two parties on successive evenings in mid-December and I’ll be on my feet for the duration, while guests’ glasses are filled, introducing actors to politicians, academics to sportsmen, scientists to singers.

But I’ve been going to a funeral or memorial service a week lately. So it’s time to end the tradition before we’re completely depleted.

Mary and I have adhered to the same formula for the entire four decades. Why change something that works?

My wife Mary and I (pictured together) will host our last champagne and shepherd’s pie party at our London penthouse overlooking the Thames

My very dear friend Margaret Thatcher, who appointed me Deputy Chairman of the Conservative Party in 1985, came to our parties for 30 years

The wonderfully erudite and witty Barry Humphries was also a frequent guest. He was such a show-off and would move around teasing everyone

We always serve shepherd’s pie — which I love — and champagne which I don’t give a damn about. I drink water or Diet Coke. A party host should always be 100 per cent sober.

Guests like the fact that they know what they’re getting. You shouldn’t arrive wondering what you’re in for. Ninety per cent of the people we invite — each one we count as a friend — are regulars who have been coming for ten or 20 years so they know exactly what will happen.

Champagne will be served throughout the evening, which starts at 7.30pm.

A choir will sing four carols, then there will be a few canapes before the shepherd’s pie is served. Five carols follow supper and then it’s home by 10pm, at which point Mary hands all the guests a parting gift of a round of cheese.

Somerset cheddar, of course. (I am, after all, a West Country boy: Baron Archer of Weston-super-Mare.) The cheese has a special label featuring scurrying mice, created by the wonderful artist Peter Cross, who also designs our invitations.

I will not tell you which Secretary of State tried to engineer getting two cheeses. He accepted his, then his wife came round for a second, quarter of an hour later — we suspect on her husband’s suggestion. My late secretary Alison told her: ‘I’m awfully sorry. We’ve already given your husband a cheese.’

A few stragglers might stay until 10.30pm. Nobody gets drunk — it’s not that sort of party — and we have never had to eject anyone for bad behaviour, although once I spotted a guest handing out his business card (networking is entirely forbidden as I do not want my guests to feel under pressure) and he was not invited again.

My very dear friend Margaret Thatcher, who appointed me Deputy Chairman of the Conservative Party in 1985, came to our parties for 30 years.

We always serve shepherd’s pie — which I love — and champagne which I don’t give a damn about. I drink water or Diet Coke. A party host should always be 100 per cent sober

We don’t permit photos, so everyone can relax. Joan Collins is a regular. She is just such an easy-going, warm person, delightful to chat to and naturally outgoing

I remember the actor Donald Sinden flirting with her, which was a sight to behold. Donald had a wonderfully rich, plummy voice and such charm. Of course Margaret was won over.

Margaret was as much a friend of Mary’s as mine. They had much in common: both read Chemistry at Oxford and Margaret was an undergraduate at Somerville College where Mary later taught.

There was always so much for them to talk about and when Mary was chair of Cambridge University Hospitals NHS Foundation Trust — a role she held for ten years until 2012 — Margaret’s idea of a fun afternoon was to pop in and watch an operation with Mary while Denis Thatcher and I went off to a rugby match.

Long before it became fashionable we had a strict ‘no smoking’ rule at our parties, which Denis would flout. He was the only guest who dared, so someone would follow him round with an ashtray. I’ve always liked the fact that an extraordinarily diverse range of people come to the parties.

We don’t permit photos, so everyone can relax. Joan Collins is a regular. She is just such an easy-going, warm person, delightful to chat to and naturally outgoing. I always enjoy her parties as well.

The wonderfully erudite and witty Barry Humphries was also a frequent guest. He was such a show-off and would move around teasing everyone.

On one occasion we were looking at some oil paintings when Mary walked into the room. He looked at her and said: ‘I have one word that encapsulates you.’ Then he put his arm round me, looked at her and said: ‘Tolerant.’

Dear and loyal friend that he was, he should never have gone to Australia on that final trip where he died in April this year.

In years past perhaps it would be Betty Boothroyd, the former Speaker who died in February, chatting to the late Cilla Black

I saw him at the flat three days before he flew out. He gripped my hand as he was leaving and said: ‘We really must see more of each other.’ I said to Mary: ‘I don’t think we’ll ever see him again. I think that was his goodbye.’ And I was right. He was as funny as he was incredibly clever. We once gave a dinner when he was guest of honour, as Dame Edna, at the hospital open day in Cambridge. He was with some towering intellects from the university and he more than held his own.

Everyone dresses smartly at our parties, although there is certainly no dress code. I usually wear a velvet jacket and a Christmas bow tie, and as the champagne is poured I’ll mingle, introducing people who I think might not have met each other. So I might introduce Seb Coe — now a life peer and former Olympic champion — to Martin Rees, who is the Astronomer Royal and Emeritus Professor of Cosmology and Astrophysics at Cambridge.

Or in years past perhaps it would be Betty Boothroyd, the former Speaker who died in February, chatting to the late Cilla Black.

Cilla didn’t ever sing but Shirley Bassey did. Dear Shirley. She hasn’t been able to attend for the past couple of years but we always get a warm message in her Christmas card apologising because she couldn’t make it.

And although I’m a Conservative we have socialist guests as well. Betty, the first woman Speaker of the House of Commons, was eminent among them.

I think the oldest person coming this year will be the Labour peer Bernard Donoughue, who headed Lord Wilson’s No 10 Policy Unit. He is 89. He, like me, can’t stand for too long these days so he’ll probably only stay an hour or so.

Over the years I think four or five prime ministers have been guests. Alec Douglas-Home came to the first party in 1983 as did Jack Profumo, Harold Macmillan’s secretary of state for war.

There was an amusing occasion when John Major was PM. He was having a particularly hard time with the Press about Europe at the time and arrived late with Sir Murdo Maclean, then a senior civil servant working in the whips’ office. Murdo kept urging John to return to Downing Street as there was important business to be done but John was very keen to stay and enjoy his shepherd’s pie.

Everyone dresses smartly at our parties, although there is certainly no dress code

Murdo insisted: ‘Really I think you need to get back to No 10,’ and John was equally adamant that he didn’t want to leave.

Then Nicky Swinburn — our wonderful cook from Newmarket who has done our catering for decades — dashed out of the kitchen to inform me the German chancellor was on the phone for the prime minister. He left immediately to take the call and the rest of the kitchen staff disappeared into the corridor, which made me chuckle.

Over the decades there hasn’t been any scandal to report. The most shocking thing I can tell you is that Tom King, then defence secretary under Margaret Thatcher, actually came to both parties one year. Nobody gets invited to both nights in succession so on the second evening I asked him politely: ‘What brings you back again, Tom?’

He explained that half his protection team had come with him to the previous night’s party and had enjoyed their shepherd’s pie in the kitchen so much that the following night the other three members of the team didn’t want to miss out.

Everybody loves the shepherd’s pie — although the vegetarians get a meat-free option — but Nicky will never disclose the recipe. It will remain a closely guarded secret, despite the clamour of requests from guests every year.

I can allay one apocryphal story, too. Contrary to many reports over the years, I have never told guests the way to the loo is ‘left at the Picasso and right at the Hockney’. There is some truth in it, however. To get to the lavatory you go past the Picasso and right at the Monet. But no. I’ve never actually said it.

Usually the living room is cleared of all the furniture for the two days of the parties to make space for guests. The removal men come in and pile it into one of the bedrooms. It is all organised to the nth degree.

In her later years, Margaret Thatcher, as she became more frail, was the only guest to be given a chair. People queued to talk to her, which I found quite touching.

 A choir will sing four carols, then there will be a few canapes before the shepherd’s pie is served. Five carols follow supper and then it’s home by 10pm, at which point Mary hands all the guests a parting gift of a round of cheese. Pictured: Lord Archer with his wife Dame Archer

The choir stand at different levels on the sweeping stone staircase that leads to the mezzanine to sing. There is plenty of room for the guests in our L-shaped living room. A wonderful vista over London from Battersea power station to St Paul’s Cathedral unfurls through giant windows overlooking the Thames, and the lights of our great city twinkle festively at night.

There won’t be any fireworks — there never have been — or any disruption in the basic routine, even though it is our final farewell.

The wonderful choir, called Tenebrae, always sing my favourite carols, among them The First Noel, Silent Night, Good King Wenceslas and We Wish You A Merry Christmas, which is their finale.

Mary, who is a serious singer and musician, always asks for a couple we have never heard before, which are esoteric and clever. These appeal to the dozen or so guests who enjoy esoteric and clever music.

There is quite a story behind how the choir first came to the party. Many years ago the late George Solti, who was then principal conductor of the London Philharmonic, hired Tenebrae for me as a party gift. He knew exactly what he was doing, cunning old thing.

After they sang for us, so many of the thank you letters were effusive about them. Everyone said: ‘We loved the choir!’, so Mary suggested: ‘We’ll have to have them next year.’ Since then they have become an integral part of the evening.

However they were performing in Switzerland on the days we usually have the parties (the second Monday and Tuesday in December), so we moved the dates to the Wednesday and Thursday to accommodate them.

There will be just a couple of minor tweaks to the proceedings this year. I will be giving Mary a present to celebrate her ninth and final year as chair of the Board of Trustees of the Science Museum in London. She will be retiring at the end of December.

And Tim Rice will recite the periodic table. It might sound an odd thing to do but Mary sang the periodic table at my 80th birthday party. Tim thought it would be a great test of his memory — he is now 79 — if he could also learn it by heart.

I said: ‘Why don’t you recite all the elements at our final Christmas party?’ and he agreed. A hell of an achievement if he can commit all 118 to memory. I’m sure I couldn’t.

So Mary and I are looking forward to this final Christmas valediction with the old friends who are still with us. Someone suggested we would not keep to our resolution that it should be the last party. I can assure you we will. The decision has been made.

Our sons William and James will be there with our eldest grandson, ten-year-old Alexander; his first and last party. If there are to be any more of them, it will be the next generation’s turn to step up.

The parties have been a great part my life but, to use a well-worn cliche, all good things must come to an end.

• Traitors Gate, Jeffrey Archer’s latest book, is out now in hardback, published by HarperCollins, price £22.