Green told PRWeek that there were "serious questions about openness and transparency" for Cratus, which was founded by Kevin Davis before he became the Conservative leader of Kingston Council this spring.
However, Davis hit back, accusing Green of "playing stupid games trying to trash people’s reputations without evidence of wrongdoing".
The row centres on Cratus’ hiring of Bob Neill, the Tory MP for Bromley & Chislehurst and a former local government minister, as a non-executive director, which it announced on 23 June.
This raised some eyebrows in the lobbying industry because the code of conduct of its self-regulatory body, the Association of Professional Political Consultants, precludes member agencies from employing MPs.
It has since emerged that Neill has yet to disclose the directorship on the monthly register of MPs’ financial interests – however, he and Davis have insisted that this is nothing untoward.
Neill claimed he had not yet become a director of Cratus, nor had he received any payment from the agency, though he added that he anticipated taking up the directorship "shortly" and "all necessary registrations will be made".
Although the MP has been featured on the agency’s website as a non-executive director, his assertion is backed up by Companies House records and by Davis.
According to Companies House Cratus registered five other directors between 23 July and 4 August, including another non-executive, Tim Grier, but not Neill.
Davis initially said the reason for the delayed registration was that Cratus "had other executive directors to appoint and organise" and later "because we have just not completed it".
Davis said: "Bob Neill has not been paid anything and we would (I believe) have 28 days to register the interest after payment."
Neill added: "I have had no dealing with Cratus clients, and have raised no issues in Parliament relating to them. I have at all times precisely followed the advice of the House authorities and, of course, will continue to do the same."
Parliament’s code of conduct allows MPs to work for lobbying agencies as long as they declare their interest – including when they have an expected future interest – when speaking in proceedings of the House.
It is not clear whose interests Cratus represents because it does not disclose its clients – something it would have to do were it a member of the APPC.
Green, who leads the Liberal Democrat group on Kingston Council, said: "There are clearly serious questions about openness and transparency here regarding Kevin Davis, the Tory Kingston council leader, and the business interests of his lobbying firm.
"Especially when, unlike other lobbyists, his company does not abide by the industry body's code of conduct, does not declare clients publicly on the APPC register, and has a sitting Tory MP and former minister due to join the board who hasn't even declared this formally in Parliament."
Hitting back at Green, Davis said: "This is not an issue of transparency as all the statutory regulations that need to be complied with have been. We have enforced our own code of conduct on our website which people can easily read and download and I have personally complied with all the requirements put on me by local government regulations.
"In addition we have agreed not to work in any local authority area where any employee or director is elected. This is clearly more about a grumpy former Lib Dem council leader who can't get used to the fact she lost her party control of the council in May 2014 and wants to play stupid games tying to trash people's reputations without evidence of wrongdoing."
Neill was unavailable for further comment in response to Green.
Transparency row over Tory MP's role with lobbying agency
The former Liberal Democrat leader of Kingston Council, Liz Green, and her Conservative successor Kevin Davis are in a war of words over the transparency of local government lobbying agency Cratus' relationship with Tory MP Bob Neill.
