Barack Obama: A fan of the HP series

The President made a beeline for Miss Rowling, at the end of the Downing Street G20 dinner, and told her that he had read all her books himself and to his children Sasha and Malia.

Miss Rowling then received a second presidential seal of approval for the boy wizard from Russia's President Medvedev and his wife Svetlana, who not only admitted to having read the Harry Potter books but also asked for her autograph.

The US and Russian Presidents met up with them for coffee after enjoying their own dinner with Mr Brown and other fellow statesmen.

Ruth Jones, the actress from the television comedy Gavin & Stacey, was the life and soul of the party. She brought the house down when she announced loudly that she had thrown her crested invitation into the rubbish bin. She had assumed it was an April Fool's Day trick given the date of Wednesday's dinner.

The spouses' dinner guests were seated across four tables, with JK Rowling and Dame Kelly Holmes seated in prime position with Michelle Obama between them on table one. Dame Kelly and Mrs Obama had a long conversation about London's successful 2012 bid as the Obamas are backing as bid to stage the Olympics in Chicago, their home city, in 2016.

The Italian Prime Minister Silvio Berlusconi was seen deep in conversation with the model Naomi Campbell. Mrs Brown's mother, Pauline Macaulay, 71, was also present.

The menu was not only prepared by Jamie Oliver and a team from his Fifteen restaurant, but the celebrity chef waited on the women and afterwards joined them with his apprentices still dressed in their chef whites.

As talk of a $1 trillion bail-out dominated Thursday's G20 conference, Mrs Brown took the wives to the Royal Opera House for a morning of high culture. J K Rowling, who wore a pale pink shift dress, read extracts from her latest book, The Tales Of Beedle The Bard which was a best-seller last year. Mrs Obama dazzled in a bright blue Jason Wu dress and cardigan with pearls. Maggie Darling, the wife of the Chancellor, joined the gathering.

Highlights of the programme introduced by the TV presenter Mariella Frostrup included an extract from Igor Stravinsky's ballet The Firebird and a short show by dancers from Ballet Black, a troupe set up to give performing opportunities to black and Asian classical dancers.

After the entertainment, the women took to the stage for a photo with dancers who were rehearsing for a production of Giselle. Laureen, the wife of Stephen Harper the Canadian Prime Minister, declared to her counterparts: "I will never be on the stage, this is my one and only chance."