William Shawcross, chair of the Charity Commission, asked an incoming commission board member to meet the author of the controversial Sock Puppet report to discuss political campaigning, emails show.
Documents released under the Freedom of Information Act show that, in 2013, Shawcross asked the incoming commission board member Gwythian Prins to meet Christopher Snowdon of the Institute of Economic Affairs, who in 2012 published a report arguing that government funds should not be used by charities to lobby politicians.
The research, which was criticised at the time by the National Council for Voluntary Organisations for failing to show an understanding of the work charities do, was used by the Cabinet Office in February to justify its new anti-lobbying clause, which will prevent charities from using funds from central government grants to lobby.
The commission denied any involvement in the drawing up of the anti-lobbying clause and said it was a matter for government and the organisations that received grant funding.
An email from Prins to Snowdon, dated 7 May 2013 and with the subject line "political campaigning", said: "The chairman of the Charity Commission, upon whose board I shall shortly start to serve, has asked me to talk to you about matters of mutual interest.
"I shall be happy to do so," he wrote. "This issue is no flash in the pan."
An email from Snowdon to Prins, sent on 16 October 2013, said: "We spoke a few months ago about the issue of state-funded charities lobbying the government. I’m in the process of writing about this subject again for the IEA, with a particular focus on what can or should be done. I wonder if you are free to talk about this some time before the end of the month?"
Snowdon told Prins in November 2013 that he thought there were some things the commission could do on the issue of state-funded groups, but most of the responsibility lay with the government.
"If you think the commission could do more, I would genuinely love to hear your suggestions," wrote Snowdon.
In March 2015, Eric Pickles, at the time the communities secretary, said his department had introduced a new "anti-lobbying, anti-sock puppet clause" when giving grants to charities and urged the rest of government to follow suit.
Last month, Matthew Hancock, the Minister for the Cabinet Office, announced that from 1 May a new clause would be inserted into all new or renewed grant agreements with central government stating that the funding could not be used to fund activity intended to attempt to influence parliament, government or political parties.
Sir Stephen Bubb, chief executive of the charity leaders body Acevo, said the emails raised a number of questions.
"First, why did William Shawcross direct Gwythian Prins to engage with this particular think tank? Second, what was the content of the conversation between Mr Prins and Christopher Snowdon? And finally, what is the position now held by Mr Shawcross and Mr Prins regarding the anti-advocacy clause?
"To be either indifferent to or ignorant of the harm this clause is already causing, and the self-censorship it is already engendering in our sector, would be a dereliction of duty on the part of the regulator’s highest officers. Charity leaders, volunteers and workers deserve answers."
A spokesman for the Charity Commission said the regulator was not consulted by government on the anti-lobbying policy "nor was it involved in its development".
He said: "This is a matter for the government and the organisations that are in receipt of those funds.
"As part of its duty to be a competent regulator, the Charity Commission, its staff and board members regularly meet interested parties who work in the same sector. This includes charities and umbrella bodies across the spectrum. This work is a vital part of being a modern, effective, outward looking regulator."
Prins said in an interview with Third Sector in 2013 that the public expected charities to "stick to their knitting".