In the frame: the President, the ladies who launch and the art world's biggest players

What links Vladimir Putin to Princess Margaret's bridesmaid? And what will Charles Saatchi make of it? Nicholas Pyke reports

It is an unlikely pairing. One, a publicity-shy member of the British aristocracy, was bridesmaid to Princess Margaret. The other is a grim-faced former KGB man who spent his early career opposing everything she stands for, including her interest in big-ticket paintings.

It is an unlikely pairing. One, a publicity-shy member of the British aristocracy, was bridesmaid to Princess Margaret. The other is a grim-faced former KGB man who spent his early career opposing everything she stands for, including her interest in big-ticket paintings.

Yet this week Vladimir Putin and Lady Angela Nevill will find themselves thrown together, named as two of the most influential power-brokers in the world of international art.

Art and Auction magazine, the house journal for dealers and collectors, has produced an authoritative new portrait of the multibillion-pound trade in art works, valuables and antiquities.

Recently acquired by London-based millionairess Louise MacBain, the magazine says that it wants to open up a trade still marked by caution bordering on secrecy. Although the magazine's Power List includes established giants such as US dealer Larry Gagosian and celebrated Italian architect Renzo Piano, it also features dozens of important players who rarely allow their photograph to appear in public, preferring to remain in the shadows of Bond Street and the New York auction rooms.

British-based experts are strongly represented, in line with London's position as a world centre of the gallery trade, and account for 18 of the 100 figures judged most influential in the last 12 months.

They include Charles Saumarez Smith, director of the National Gallery, cited as a defender of the country's artistic heritage for helping save Raphael's The Madonna of the Pinks from the clutches of the US Getty Museum earlier this year. Charles Saatchi, the champion of British artists such as Damien Hirst and Tracey Emin, lost part of his collection in the Momart warehouse fire, but remains "Britain's premier contemporary taste-maker" says the magazine. The London practice of Iraqi-born architect Zaha Hadid is a growing force, buoyed by winning this year's Pritzker Prize, architecture's equivalent of a Nobel.

Other major figures remain little known, despite their influence. Julia Peyton-Jones, 52, director of the Serpentine Gallery in London, is said to have transformed it from "ramshackle to robust" since taking over in 1991.

Few outside the art trade or the Royal Family have come across Lady Angela Nevill, but the 56-year-old is one of the most important figures in the London trade. She runs a discreet gallery next to St James's Palace, with sales of impressionist and modern works worth £17m last year. Lady Angela is chairman of the Society of London Art Dealers, credited with persuading Tony Blair to preserve Britain's status as a low-tax art market.

Elsewhere, Friedrich Christian "Mick" Flick's contemporary collection in Berlin remains at the cutting edge, although the Mercedes heir struggles to escape the taint of a grandfather with Nazi links. Larry Gagosian's expanding empire now accounts for three US galleries and two new ones in London.

The magazine says it was also a good year for Italian architect Renzo Piano, currently involved with five projects at American museums and galleries.

President Putin appears on the Power List thanks to the huge purchasing power of the Russian state and the country's new determination to reclaim its artistic heritage - much of which was spirited abroad after the 1917 revolution.

Lady Angela Nevill

Judged the most influential figure in the London art world, Lady Angela, a former bridesmaid to Princess Margaret, is impeccably connected but wary of publicity. Aside from running her own gallery in St James's, the 56-year-old heads the Society of London dealers and launched Art Fortnight London, which has promoted the London gallery world more aggressively than ever before.

Julia Peyton-Jones

Described in the new Power List as the most glamorous museum director in London, Peyton-Jones, right, heads the Serpentine Gallery in Kensington Gardens. The 52-year-old is praised for her success in professionalising an institution that was once dismissed as "ramshackle".

Zaha Hadid

The London-based architect is exerting growing influence around the globe. Born in Iraq, the 54-year-old first came to Britain in the 1970s to study. Earlier this year she won the Pritzker Prize, architecture's equivalent of the Nobel. Hadid is currently involved with major building projects in Rome, Copenhagen, Moscow and Taiwan.

Charles Saumarez Smith

The director of the National Gallery played a leading role in this year's successful campaign to keep Raphael's 'Madonna of the Pinks' in Britain, despite interest from America's Getty Museum. The 50-year-old is a fully signed-up establishment figure, educated at Cambridge and a former head of the National Portrait Gallery.

Larry Gagosian

The celebrity art dealer known as Gogo represents many of the world's richest collectors in trademark high-visibility style. The 59-year-old also has a growing gallery empire, including one in Regent Street and another, opened this year, at King's Cross.

MacBain is the missing name on the Power List

One notable absentee from the Power List is the magazine's new publisher, Louise MacBain, who is herself emerging as one of the most the influential woman in British art.

Mrs MacBain, a friend of Prince Andrew with a fortune reputed to stand at $500m (£264m), has been described as a future George Soros of the gallery world.

The 44-year-old Canadian has already amassed a formidable collection, including pieces by Damien Hirst and Antony Gormley. Her company, LTB Holding, has also acquired a series of international art publications with a combined readership of 14 million, including Art and Auction, one of the few magazines that is guaranteed to reach the world's top dealers.

In the New Year she plans to open a new multimillion-pound arts centre in west London, not far from her Holland Park home.

It will be home to the Foundation Blouin MacBain, a charity which promises a series of big money prizes, which aims to promote British art and theatre to lucrative foreign markets, and to sponsor a schools programme.

Mrs MacBain has already found a way into the diaries of the Prime Minister as well as the Secretaries of State for Education and Culture.