The Tax Payers' Alliance (TPA) describes itself as "Britain's independent grassroots campaign for lower taxes...The TPA is committed to forcing politicians to listen to ordinary taxpayers."
Averaging 13 media appearances daily, the TPA's proposals for a public sector pay freeze were recently adopted by David Cameron.
"We believe in low taxes, public sector reform and personal freedom," said TPA founder Matthew Elliott. "But the idea that that puts us in cahoots with the Tories is laughable."
Elliott was previously an assistant to a Tory MEP, and co-founder Andrew Allum was a Tory councillor. TPA director Alexander Heath lives in France and doesn't pay British tax.
The TPA board now includes Saul Haydon Rowe (of Devon Capital LLP), Ruth Lea (ex-Lehman Brothers) and Mike Denham (former tax adviser to Margaret Thatcher).
The TPA keeps its accounts secret, but its £1 million annual income has been helped by Midlands Industrial Council, which has donated £80,000 - after the £1.5 million given to the Tories since 2003. JCB tycoon Anthony Bamford also donates to the TPA - alongside the £1 million his company and family have given to the Tories.
At TPA meetings you can see speakers such as Tory chair Eric Pickles, shadow minister Liam Fox and Daniel Hannan MEP (who claims the NHS is "a 60 year mistake"). The TPA also campaigns against what it claims is "hate education" in Palestinian school textbooks, and has now launched "Big Brother Watch", run by Alex Deane, former chief of staff to David Cameron, who uses his blog to rage against legalising drugs and abortion.
"Perhaps our time will come next year if there are public sector strikes," suggests Elliott at the prospect of a Tory government. "That will be a key recruiter."
But "we are not a hypocritical Tory front group", says Elliott.