The Electoral Commission is considering allegations that millionaire Tory MP Zac Goldsmith breached election spending rules when he won his Commons seat in May.
The environmentalist – who has advised David Cameron on green issues – has donated £264,000 to his local Conservative association in Richmond Park since 2007, which is believed to be a record for a candidate. He won the seat from the Liberal Democrats' Susan Kramer with a majority of 4,091.
According to Channel 4 News, Mr Goldsmith reduced the real cost of spending on campaign materials – including 200 blue "I back Zac" jackets for his supporters – so that his official returns remained below the legal limit of £11,003 in the 23 days up to polling day. His team says it obeyed the spirit and letter of the law.
Mr Goldsmith's declaration, signed on 7 June, states that he came £220 below the ceiling with a campaign total of £10,783. But invoices for some materials he bought show they were reduced by 90 per cent on his return, enabling him to stick within the overall limit.
For example, his team spent £2,800 on 600 signs, but said only £262 was spent on them during the campaign period. A quarter of the costs of the signs – some £700 – was moved from Mr Goldsmith's own personal parliamentary campaign on to the expenses of local Tory candidates in the Richmond Borough Council election, which took place on the same day – even though they all appear to bear his face and name.
One invoice gave the full cost of the 200 jackets as £2,168. But the figure on the return was reduced by 90 per cent to just £170 on the grounds that not all of them were used.
The Goldsmith team ordered 272,000 posters and leaflets, costing more than £14,000 – enough by itself to take him over his spending limit. The campaign said he did not use 62,000 of them, cutting his spending declaration by more than £2,500.
An Electoral Commission spokeswoman confirmed it had received information from the Bureau of Investigative Journalism, which worked with Channel 4. The commission is to carry out an initial assessment over the next few days and decide if the matter requires a full inquiry. A breach of the rules can result in an MP being barred.
Mr Goldsmith said last night that his campaign spending declarations were "exactly the same" as other candidates. "We were probably even more careful than most, because it was a high-profile campaign in a hotly contested seat, and it was inevitable that we would be examined afterwards," he said in a statement. "Channel 4 have specifically focused on my returns because it guarantees them extra coverage... This is no more than shoddy and sensationalist journalism."
A Channel 4 News spokesman said: "We refute any suggestion that Zac Goldsmith was targeted simply because he is a high-profile figure. The issues we found regarding Mr Goldsmith's campaign expenses are materially different and of a different scale to those found in other returns we looked at. Channel 4 News stands fully behind its report which was rigorously researched."