LONDON — Behind the front doors of some of the most exclusive addresses in central London, key members of the U.K.'s political elite eat, drink, meet and sleep — and find a comfortable and discreet location for deals and political advancement.

Although the world of members-only (and sometimes men-only) clubs is no longer a central part of the fabric of British politics and a badge of political tribe, many of the British political class still see membership of these historic institutions as a key part of Westminster advancement. Others see them as a quiet place away from prying eyes or for a quiet evening away from politics.

"Obviously the best club in London is the House of Commons and it is a great place to meet people and see people, but sometimes it is quite handy to have somewhere out of the House when you want to have a quiet evening, or a drink," said former Foreign Office minister Henry Bellingham, who is a member of the men-only White's club.

"Going back 100 years, there were a lot of ministers and MPs for whom club membership was more important because they would spend much more time there. Now, when the House is sitting, people spend more time in parliament."

One issue is the cost, with membership sometimes running to £1,000 or more annually. "There still are these political allegiances [to clubs] but it is reduced for that very simple pounds, shillings and pence reason," said Howard Flight, a former MP and now member of the House of Lords who is a member of three London clubs — the Carlton Club, Pratt’s and Boodle’s. He said he now does most of his entertaining within the Palace of Westminster.

Bellingham believes that younger lawmakers are seeing the value of a more private space — "another ambience where you can meet old friends or do business."

"What strikes me in the clubs I tend to go into ... White's as a member, others as a guest ... is the number of young people around," he said.

With the help of club listings in the pages of Who's Who, here's a peek through the keyhole of some of London's most exclusive clubs and at their influential political members.

The Carlton Club

You don't get much more Conservative than the Carlton Club, founded in 1832. "Membership was a badge of allegiance to the Conservative Party and the club provided the core of the party’s organization for many decades, particularly before the foundation of Conservative Central Office," its website says.

Tory MP members are numerous and Conservative prime ministers, including Theresa May, receive honorary membership of the St James’s Street club.

May resigned in 2001, along with her former first secretary of state Damian Green, over the club's men-only membership policy. At the time women could be associate members, but could not use the gentlemen’s bar or vote for officials. Former Prime Minster David Cameron refused to join on similar grounds but became a member when the club granted full membership to women in 2008.

Female MPs who are currently members include Harriet Baldwin, Nadine Dorries, Rachel Maclean and Victoria Prentis, who chairs the club's political committee.

The Beefsteak Club

Four of the government's Foreign Office ministers, including Foreign Secretary Boris Johnson, are members of the men-only Beefsteak Club.

Discretion is key. A number of club members did not respond to requests for comments. One member said patrons were rigorous about not talking about the club outside its walls.

But reports about the club, on Irving Street, suggest that members dine together at one table with their guests. Tradition dictates that the club steward and the waiters are all addressed as "Charles."

Foreign Office ministers Alan Duncan, Hugo Swire and Rory Stewart are also members, along with former Chancellors Norman Lamont and Nigel Lawson, ardent Brexiteer and former MP Peter Lilley and Nicholas Soames, the grandson of Winston Churchill.

Club member Stanley Johnson (father of Boris) reportedly attempted to block Environment Secretary Michael Gove from joining. The pair had fallen out during the 2016 Tory leadership contest, in which Gove ended Stanley's son's chances of becoming PM.

Pratt’s

A men-only club with a long list of current and former Tory MPs as members. Howard Flight described it as "very characterful and eccentric."

Etiquette dictates that you sit for dinner at a round table at the next available chair, next to someone "you might find has been running a country in Africa 20 years ago," said Flight.

"There are all sorts of interesting and characterful people."

Like the Beefsteak, serving staff have a single name, with men referred to as “George” and women referred to as “Georgina.”

Conservative MPs who are members include Edward Garnier, James Gray, Adam Holloway, Swire and Soames.

Peers among its membership include former Deputy Prime Minister Michael Heseltine, former Conservative leader Michael Howard and Lawson. Former Prime Minister John Major is also a member.

White's

Cameron resigned from White’s in St James’s in 2008. Its ban on women did not sit with his attempt to depict himself as a modernizing Tory leader.

But a number of Conservatives continue to list membership in Who's Who, including Heseltine, Lamont, Soames, Swire and Bellingham.

Bellingham described it as "quite a traditional Conservative bolthole." It is relatively small, does not have many functions and is quite low profile, he said.

He uses it both for social and political purposes. "If I want to have a quiet meeting with someone outside the House [of Commons], then it is quite a good place to go because you haven't got people breathing down your neck the whole time. Parliament is great, but if you are having a meeting with a minister or colleague, people are always around or interrupting or what have you, so it is not quite so satisfactory."

Bellingham defended its men-only policy on the grounds that it is "very small."

"There has not been demand for members' wives or women to join and I think its characteristics, its whole atmosphere is based around being men only."

He described private clubs as like a private house, and said he believed it was fine to have a men-only policy if it was not getting a public subsidy or tendering for public events.

The National Liberal Club

Founded in 1882 by Liberal Prime Minister William Gladstone, the Whitehall Place club — complete with billiards room that members can book for "inter-club challenges" — has former Liberal Democrat leaders Nick Clegg, Paddy Ashdown and Menzies Campbell among its members. H.H Asquith, Winston Churchill, David Lloyd George and Ramsay Macdonald are among its former members.

Civil servant Ollie Robbins, Theresa May's trusted EU adviser, is also a member, along with king of the pollsters John Curtice — although he said he has "not been in the place for ages." He said he mostly uses the Royal Society of Arts when he needs somewhere in central London to work.

The Garrick Club

The Garrick Club, founded in 1831, is in the heart of London’s West End. It boasts a theatrical library that includes many original manuscripts and documents, along with a comprehensive collection of theatrical paintings and drawings.

Leader of the soft-Brexit rebels Dominic Grieve, whose pre-Christmas EU (Withdrawal) Bill amendment inflicted defeat on the government, is a member, along with fellow Tory Remainer Ken Clarke.

Former MP-turned-political pundit-turned-travel broadcaster Michael Portillo is also a member, along with ex-Washington Ambassador Christopher Meyer, although he said he does not use such clubs often. "When I do, it's for the companionship, ambience, food and wine, in no particular order. Some are islands of tranquility in a busy city. There is no political significance to my membership of any of them," Meyer said.

The Marylebone Cricket Club

Membership of the Marylebone Cricket Club — the owner of Lord’s cricket ground and the guardian of the laws of the game — has its fair share of politically-connected members.

Department for Exiting the European Union Director General Alex Ellis, former Justice Minister Crispin Blunt, former Permanent Secretary to the Exchequer Nicholas MacPherson and Boris Johnson's former special adviser Will Walden — now managing director of public affairs and government relations at Edelman — are members of the renowned institution.

Walden, who has been a member since 2001 (but was proposed on his 16th birthday in 1987) said for him, membership was about being a "custodian of cricket's traditions" and "playing a small part in guiding and directing cricket's future and guarding its integrity."

"The days of smoky corners and old boy networks are thankfully pretty much long gone. To be honest I use the club as much to get away from politics as to talk politics. Cricket runs through my veins, it's my passion and my relaxation, so on match days it's generally runs and wickets not bills and Brexit," he said.

"Membership does however provide you with that most invaluable of political currency — test match tickets at Lord's — political opponents can suddenly appear very keen to be your friend," he added.

East India Club

Founded in the middle of the 19th century, the club's original members were workers in the East India Company and commissioned officers in the army and navy.

Former United Kingdom Independence Party leader and ardent Brexiteer Nigel Farage has been an active member since joining more than 20 years ago.

The self-styled gentlemen's home-from-home is "not a very political place," according to Farage. He said he has used its meeting rooms for significant gatherings, although he remained tight-lipped about when and who was there.

“It is a lovely discreet place where you can meet people where you are unlikely to finish up in the gossip columns,” he said.

It has "as good a traditional menu as you will find anywhere in London at a fraction of the price," he said, also praising the club's real ale and value for money.

He claimed there are at least two Tory MPs who are members, although he would not say who they are.

With international reciprocal arrangements, including with U.S. clubs, "you are as likely to meet a U.S. congressman in there as you are a British MP," according to Farage.

Clubs such as White's are "packed to the rafters with members of the House of Commons and House of Lords," said Farage, "The East India isn’t a political club and I also find that quite appealing."