The man behind Jeremy Corbyn's tax policies has been in talks with the Green Party and enjoyed a "friendly exchange" with a mystery Conservative minister after his ideas helped the left-winger sweep to victory in the Labour leadership election.

Richard Murphy told IBTimes UK that he had met with Natalie Bennett for tea on 16 September and recently spoke with Labour. But after hitting the headlines as the author of People's Quantitative Easing (PQE), he has also received some attention from an unnamed top Tory. "I happened to bump into him, we had a little and friendly exchange – we always banter with each other," Murphy said.

The accountant reiterated that he was open to taking a job in Corbyn's new team, but explained he would not take the role regardless. "If he wants to offer me a job and it's the right job, which will use my skills in a way that I think are appropriate and which will also fit in with my family's life, then I would do it. I'm sure I would take it," Murphy said.

The 57-year-old also confirmed he has given informal advice to Corbyn as well as working for the Greens in the past on policies such as Green Quantitative Easing and the Green New Deal. "If Caroline Lucas wants to phone up for my advice, I would give it to her as well," he added.

Murphy also said the National Health Action Party (NHA) had borrowed some of his tax policies in the run-up to the general election. "My ideas were flung around the political environment at the last election, I'm delighted by that – as I think that's what you want," he claimed.

The tax justice campaigner spoke to IBTimes UK just hours after he was interviewed by veteran journalist and top inquisitor Andrew Neil on the BBC's Daily Politics. The Scottish host forensically questioned Murphy over his economic policies, an experience Murphy said he prepared for.

"I went in resolved not to deal with any nonsense. For example, when he started making a silly assertions about Venezuela, I simply refused to engage with him – I said: 'This is just not relevant, I'm not going to play on a silly territory that you define that has nothing to do with the debate that we are doing here,'" he said.

But despite his association with Labour and Corbyn, Murphy will only say he did not vote Tory in May and revealed he would have been purged from the Labour leadership election if he attempted to take part.

He said: "If Labour had gone through my application, they would have noticed that I have worked for the Green Party and they would have chucked me out straight away. So as the author of Corbynomics, there's no way that I would have been able to vote. I didn't try, I didn't register."