Plain cigarette packaging: Labour urges Cabinet Secretary Jeremy Heywood to intervene over Lynton Crosby 'lobbying'

Labour have attempted to ratchet up the pressure on Britain’s most senior civil servant to intervene in the row over allegations that the Conservatives’ election guru used his position to lobby ministers on behalf of private clients.

Yesterday, Sir Jeremy Heywood, the Cabinet Secretary, told Ed Miliband that he would not launch an inquiry into whether Lynton Crosby had used his position to lobby David Cameron against the introduction of plain cigarette packaging.

Alongside his letter he published what were described as the “principles of engagement” between Mr Crosby and the Conservative Party, which appeared to suggest he had agreed not to use his position to advance the interests of his firm’s other clients.

But it later emerged that the agreement had been “written” just two days earlier and that civil servants had had no involvement in drawing up the terms of the deal – which was described as a verbal agreement.

Today, Jon Trickett MP, Labour’s shadow Minister for the Cabinet Office, wrote to Sir Jeremy pointing out that there was a “significant lack of clarity” over who Mr Crosby’s clients are, and “whether either the Government or the Conservative Party have any idea who they are”.

He asked Sir Jeremy when he first saw the principles of engagement, whether any civil servants were involved in the drawing them up and whether he was “personally satisfied” that Mr Crosby has had no discussions with the Prime Minister or ministers about tobacco or alcohol policy, the NHS or fracking.

A Conservative spokesman said Mr Crosby had already denied lobbying Mr Cameron or speaking to him about cigarette packaging. “This is just a smear campaign,” they said.