Lewes MP Norman Baker was today basking in the limelight as the backbencher who brought down one of the country's most powerful politicians.

Questions about the Hinduja passport affair by the Liberal Democrat's Dome spokesman were being hailed as the prompt for Peter Mandelson's resignation yesterday.

The former Northern Ireland Secretary was forced to resign after being confronted by Prime Minister Tony Blair about his false accounts of the affair.

Mr Mandelson insisted he had done nothing improper, but accepted he had not told the whole truth about his intervention in the application for naturalisation by wealthy businessman Srichand Hinduja.

Speaking to The Argus, Mr Baker said: "It seems to me, looking at the evidence, that Peter Mandelson was not straight with Alistair Campbell and his colleagues and left the Government in a mess."

However, he went out of his way to defend the Government, saying Mr Mandelson's actions should not be compared to the sleaze which engulfed the Tories in their final years in power.

It is the biggest coup yet for the MP who was quick to establish a reputation for fearless questioning after his election in 1997.

It won immediate applause from Lib Dem leader Charles Kennedy.

He told The Argus: "Before today Norman Baker had a fearsome reputation as a tireless campaigner and investigator. Today, he has more than exceeded his past performances. He is a tremendous asset to any party which values freedom and democracy."

Tory leader William Hague was ferocious, calling Mr Blair's "career-long dependency" on Mr Mandelson "a monumental error of judgement".

Nicholas Soames, former Tory minister and MP for Mid Sussex, said it was the first time in his political career a resignation had united all sides of the House of Commons.

He said: "It's a major political event, of that there's no doubt.

"Mandelson had the attitude there are rules for the little people but not him. He had to go.

"It's the second time in 25 months his integrity has been brought into question and it must call into question the Prime Minister."

The Premier insisted yesterday he was satisfied that Mr Mandelson had not sought to influence the process improperly.

Ivor Caplin, Labour MP for Hove said Mr Mandelson had no other choice.

He said: "I think he has taken a courageous personal decision to acknowledge he got things wrong."