The portrait depicts a smiling Queen gazing towards a window dressed in robes for the state opening of Parliament.

One critic said she looked like a column

The painting, which also features two Chelsea pensioners, was commissioned by the Royal Hospital Chelsea from artist Andrew Festing.

Although the Queen has not commented on the new painting, it is believed to have been given a better reception in the royal household than the previous portrait, a 1996 work by painter Anthony Williams.

The Queen was understood to have taken an instant dislike to that portrait, which showed her with fat fingers and wrinkles.

Portrait is 'disproportionate'

The latest work has been less well received by London Evening Standard art critic Brian Sewell, who described the Queen as looking like "the female equivalent of the giant in Jack and the Beanstalk".

Mr Sewell said: "The trouble with Festing's portrait is that it is disproportionate, the Queen standing like a giant column on one side, with various trappings occupying the rest of the picture."

He said a moratorium may have to be declared on the "hackneyed" royal portrait.

Queen 'enormously helpful'

The new painting will hang alongside other state portraits in the Chelsea hospital's large collection.

Lord Archer unveiled the 6ft high work at the opening of the annual Royal Society of Portrait Painters Exhibition at The Mall Galleries, central London.

Queen hated her "sausage fingers" in 1996 painting

Mr Festing, who spent nine months working on the portrait, said the Queen had been easy to work with.

He said: "She is enormously helpful and co-operative. She's very skilful at keeping an alert expression on her face, which is very helpful, and I did give her a hint of a smile."

Mr Festing, a former captain in the Rifle Brigade, said the Queen has not commented on his work.

He said: "I do not think she comments on these things, I don't think she gets involved which I think is quite right."

Prize winners announced

The artist is a former head of the English picture department at Sotherbys and took up full-time painting in 1981.

Lord Archer commented: "I think it is outstanding, it's a very good picture."

The exhibition also features the first portrait of Ffion Jenkins, wife of the Conservative leader William Hague, by Tom Coates, president of the Pastel Society.

The winners of three major prizes were also announced today, including a new award for portrait drawing, sponsored by the Prince of Wales.

The �2,000 prize was won by Nick Cochrane, from London, for his work entitled Julian.

James Lloyd, 27, from Lytham St Anne's, Lancashire, wond the �3,000 Carroll Foundation Young Portrait Painters Award for his work Maroon Bentley and John Ward won the �5,000 Ondaatja Prize for Portraiture.