I just look perplexed - if you like that's pretty much the story of British politics

Charles Kennedy

The portraits are called "Proportional Representation" - something which had Mr Kennedy nervously asking: "What does this mean?" as he waited alongside Mr Hague for the pictures to be uncovered by Commons Speaker Michael Martin.

He soon discovered the portraits were painted by size according to the number of votes won by each party - leaving Mr Kennedy the smallest face alongside the widescreen television-sized image of Tony Blair.

With the prime minister travelling abroad, the two remaining party leaders were pressed for their immediate verdicts at what were their first view of the portraits.

Yeo says Blair was the hardest to get to relax

Mr Hague told an audience of MPs, art lovers and journalists: "They are wonderful portraits...

"I look a little calmer than Charles and it's the first time the prime minister has had me on his left and Charles on his right!"

Adding his opinion of the portraits, Liberal Democrat leader Mr Kennedy said: "I think William is absolutely brilliant, Tony is centre stage, focussed and I just look perplexed.

"If you like that's pretty much the story of British politics!"

Mr Kennedy said he liked the portrait but thought he had fewer "creases and wrinkles".

The portraits were commissioned by the House of Commons Works Committee, whose chairman, Tony Banks, said he thought it was fitting to have official election portraits in the way war portraits had been painted in the past.

"I hope this will become as much a feature of future elections as swingometers and lost deposits," said Mr Banks.

Kennedy says he looks perplexed

The Labour MP explained he came up with the idea as a way of getting around the prime minister's reluctance to sit for an official portrait.

Mr Yeo told BBC News Online said it had taken some persuasion to get the three leaders to agree to help in the projects, which meant he sat in on private meetings and travelled on the party battle buses.

"The hardest thing really was just getting them to relax," said the artist, who is the son of shadow cabinet minister Tim Yeo.

"The hardest, I suppose, was Tony Blair. He had the most to do and was the last one to capitulate."

The proportional representation concept was one of a series of ideas conceived throughout the project, said Mr Yeo.

Hague described the painting as fantastic

He thanked three politicians for agreeing to cooperate "at the worst time from their point of view, and the best time from my point of view".

The challenge of painting these "fascinating" figures at the time of greatest pressure and excitement was one he had relished.

But Mr Hague said Mr Yeo had been "no trouble at all", saying: "We did not have to sit at all, he did it as we were going around. I am flattered and honoured."

The portraits will now remain in Portcullis House, part of the Palace of Westminster, and form part of the House of Commons art collection.