The property tycoons and Ken

This is precisely why Ken's hidden donations are causing unease. Indeed, there is a whiff of brimstone about his entire fund-raising operation. The "Back Ken" website asks for cheques to be made out to the "Ken Livingstone campaign fund". But the London Labour Party told the Standard that it handles all the cash and declares it as donations, not to Ken but to the party. This effectively stops any attempt to see who is giving money to Ken's campaign.

Ken has unique powers when it comes to planning permission for big projects and it is hardly surprising that he has been assiduously courted by key figures in the property world. For this reason, many believe transparency over his financial supporters is crucial.

Trying to slip donations under the wire means, inevitably, some will look askance at the efforts Ken made on behalf of people who stand to make a great deal of money out of schemes he has backed. Why, for example, did Ken use council-tax payers' money to help the fabulously wealthy Ronson obtain planning permission for a skyscraper which, more than five years later, has yet to rise above ground level?

The Heron Tower was planned to rival the City's tallest buildings. It was to break new ground in office design with a concierge-style entrance, a huge aquarium and Michelin-grade restaurant. Ronson declared it Britain's first " sixstar" office development. Conservationists declared it a disaster. It would, they said, drastically overshadow the human scale of historic buildings nearby and obscure a centuries-old view of St Paul's Cathedral.

English Heritage fought to stop it. When the matter went to a public inquiry in 2001, just over a year after Ken took office, EH lawyers argued long and hard against the tower. They found themselves up against expert witnesses including Ken's architectural adviser Lord Rogers and the noted architect Will Alsop. Both extolled the benefits of Ronson's tower, to the extent that Alsop was asked whether he was being paid to give his evidence.

Absolutely not, he said. The next day - after a series of frantic exchanges between the inquiry lawyers and the GLA - it was explained that Alsop was indeed being paid. He was receiving £7,000 from the GLA but it was said the fee was negotiated by his staff and he was unaware of it. John Prescott eventually approved plans for the tower but Ken's role prompted a tinkling of alarm which has now risen to a clamour. The Mayor's interventions at the public inquiry took up two days and cost London taxpayers a total of £67,000. What was he up to?

MUCHhas been said about Ken's predilection for skyscrapers. He says they are part of his vision for London as a world-beating city, although some have suggested he wants them as monuments to his vanity. If that were the case, Ronson's secret gift might be considered icing on Ken's ego. But Ronson is not the only property tycoon for whom Ken has deployed his considerable powers and, it has to be said, our money.

Witness the curious case of Tony Pidgley. Ken has probably spent close to £200,000 of council-tax payers' money fighting battles for Pidgley's company, Berkeley Homes, and its subsidiary, St George. And more than mere money has been used by Ken to try to ensure Pidgley gets what he wants. Ken mobilised the might of the London Development Agency - an organisation often described as his personal piggy bank - to try to batter a London borough into submission over its opposition to one of Pidgley's ambitious projects.

It is a story that proves Ken's promise to "crush" councils that stand in the way of his developer friends was no idle threat. Berkeley wants to build a £200 million development of eight towers on Potters Field, Southwark. The company owns half the four-acre site and had been trying to acquire the rest from the owner, Southwark council. But Southwark did not want to sell. The Lib-Dem council said it wanted to build a cultural centre on its share of Potters Field, although planning permission for Berkeley's towers was granted by John Prescott in 2006, again after lobbying by Ken.

With Southwark refusing to sell the land, the scheme was stalled. Enter Ken, backed by the formidable legal team on his LDA. A spokesman confirmed to the Standard that the LDA's lawyers had examined a plan to force Southwark to sell, using a compulsory purchase order. That prospect faded last week when Southwark revealed it had entered into negotiations with Berkeley Homes, but no one doubts the CPO threat was real.

Annie Sheppard, chief executive at Southwark, warned that any attempt to purchase the land compulsorily would result in a lengthy legal battle that could cost the council-tax payer millions. So why was Ken prepared to inflict this kind of financial damage on Londoners? In fact, he has done it before, again to push through one of Pidgley's schemes.

In 2003, Lambeth council turned down an application from one of Pidgley's companies, St George, to build a 50-storey block of flats on the Thames near Vauxhall Bridge. Conservationists viewed the plans with horror. English Heritage warned the tower would damage Westminster's World Heritage site and have a "catastrophic" effect on the London skyline.

Ken rounded on English Heritage and Lambeth. In an unrestrained rant, he said "we" (who did he mean, precisely?) had already fought two major battles against critics "in the recesses of English Heritage". And he warned Lambeth: "The cost of turning down an application that has the support of the Mayor will run into millions of pounds if you lose."

Lambeth, at that time under the control of a Lib-Dem/Conservative coalition, stood firm. Councillors accused Ken of using his muscle to bully them. At one point there was a move, later abandoned, to report him to the Standards Board, the watchdog of behaviour in public life. In the end Ken's government ally Mr Prescott granted permission for the Vauxhall Tower. It has yet to be built. But, thanks to Ken, it was a victory for Pidgley.

Pidgley, 60, is a Barnardo boy who was adopted by a family of travellers at the age of four and brought up in a former railway carriage. Now the Berkeley Homes boss is a neighbour of the Queen at Windsor, where he has a 100-acre estate. His companies have revenues of close to £1 billion a year and his personal wealth is estimated at more than £120 million.

He would not appear to be the kind of person Ken would gravitate towards. Indeed, some of his schemes, including Vauxhall Tower, have included far fewer affordable homes than Ken says he wants.

Inevitably, given the secrecy surrounding Ken's donations, there will be suspicion that Pidgley is among his backers. Not true, he says. His spokesman Mark Bolland said: "Tony has confirmed that neither he nor any Berkeley companiesnor any executives has ever made a political donation to Ken Livingstone or his electoral campaign."

When we asked Ken's spokeswoman about donations from developers, this was the reply: "All fundraising for the Mayoral and the GLA campaigns is done by the London Labour Party. Fundraising is not done by Ken Livingstone personally. He is not registered as a receiver of donations. This has been checked and approved by the Electoral Commission."

That certainly was the case but the commission appears to be having second thoughts. It may rule within days that donors to Ken's campaign are brought out from behind the screen of the Labour Party and identified, as the spirit of the legislation, at least, requires.

Members of the GLA have been concerned about what they felt was Ken's unhealthily close relationship with property moguls. A cross-party inquiry produced a report, Behind Closed Doors, which found Ken was meeting developers in private before making planning decisions. Among those granted private access were Ronson and Malcolm Kerr, of a company called Montagu Evans. This firm specialises in securing planning permission for big developers.

The Behind Closed Doors inquiry was chaired by Conservative GLA member Tony Arbour, currently chairman of the Assembly's Planning and Spatial Development Committee. He told the Standard: "We were concerned that developers were getting private access to the Mayor, while there was no evidence objectors were getting the same treatment. When we asked him to open up the decisionmaking process he said: 'What, so people can see me talking to myself ?'

"The revelations about the donations make an open-and-shut case for the Mayor's planning decisions to be devolved to the Assembly."

There is no sign of that happening. Indeed, from 1 April, the Mayor picks up more planning powers under new legislation. That may be welcomed in certain quarters of the property world, but in Southwark, Lambeth and other boroughs that have dared to oppose the Mayor's friends it may be very bad news indeed.