Complainant denies sending any accusing letter

Suggestion of dirty tricks as mystery of 'Mr Jones' the accuser, who he was, and how he could have known private details

Ken Livingstone sounded his usual laid-back self yesterday as he fielded a round of media interviews about his humiliation at the hands of the MPs' anti-sleaze watchdog.

The complaint against him was nothing more than dirty tricks, he said. And while his detractors might have dismissed that, mystery deepened over the identity of the complainant.

A letter sent on 19 December last year to Elizabeth Filkin, the Parliamentary Commissioner for Standards, drew her attention to an article published in the London Evening Standard on 1 December, which said that Shaun Woodward, who was then Conservative spokesman on London, planned to complain about Mr Livingstone's earnings from his speaking engagements.

The letter was signed by a Mr John C Jones of Shepshed in Leicestershire. But Ms Filkin's clerk received a call last night from the same Mr Jones saying he had never written such a letter. Mr Jones's telephone went unanswered yesterday. Labour sources in the area confirmed he was not a party member. Nor had they ever heard from him, they said.

Even if he had made the complaint, how he would have obtained the information it contained was unclear. The article had appeared on page 26 of the first edition of the Standard, but was dropped from later editions. Mr Woodward did not make his complaint before he defected from the Conservatives to Labour on 18 December, a point Mr Jones mentioned in his letter. How "Mr Jones" knew this is unclear, though, as he had not checked either with Ms Filkin or with Mr Woodward.

Ms Filkin wrote to Mr Jones saying she was investigating his complaint, but did not hear from him until yesterday. She also wrote to Mr Livingstone on 22 December, though he is said not to have received the letter until he returned from a Christmas break on 5 January.

There was a further delay of five weeks before Mr Livingstone replied in detail on 10 February. On 31 January the new Register of Members' Interests went to press with Mr Livingstone's old, incomplete entry. It said that he had a company, Localaction, which was formed to cover his media work and the publication of the Socialist Economic Bulletin.

Ms Filkin's ruling that Mr Livingstone should have registered his interests was not published until yesterday. She was, however, available for advice previously but Mr Livingstone did not seek her help.

Now, he must lodge with the Registrar of Members' Interests a file of at least nine employment contracts - eight with public speaking agencies and one for a column with The Independent, to make the longest lodged by an MP.

But while Mr Livingstone dismissed the Standards and Privileges Committee's critical report and seemed unfazed by the prospect of having to apologise to the Commons, members of the public were seeing a new side to "the people's Ken". The man who had just advertised for £500,000 to fund his campaign for London mayor had £100,000 to put into his own coffers. Earlier, he said he had raised £70,000 for his Labour selection campaign, of which £20,000 remained.

But, he said cheerfully, at least the money he earned was not being used for personal gain. After tax, what remained would make up about a fifth of his campaign fund, while the rest would have to come from respondents to advertisements placed in the Evening Standard, The Guardian and The Daily Telegraph appealing for financial help.

Mr Livingstone's undeclared earnings in 18 months amounted to about £220,000, £158,000 of which was regular income that should have been listed.

Among his engagements, which he said were the result of speaker agencies approaching him, was a speech for Interphiz which paid him £1,500. Norman Phillips, anotheragency, paid him £1,540 for a speech. JLA paid him £12,514 for five speeches and Diana Boulter paid him £10,813 for four.

But the detail of the report contained even more shocking revelations. Apparently Private Eye's "Leninspart" is now feted in the City. Among the companies which requested him as a speaker were the accountants Price Waterhouse, the Chase de Vere finance company and the Global Real Estate Institute.