David Cameron has accepted he had a “big economic investment” in Greensill Capital but denied that motivated his intense lobbying of the Government as coronavirus struck.

The Conservative former prime minister said it was a “painful day” as he gave evidence to MPs on Thursday over his controversial lobbying of senior figures including Chancellor Rishi Sunak.

Mr Cameron placed calls and sent dozens of texts and emails to ministers and senior officials as tried to win access to Covid support programmes for the since-collapsed financial firm.

Appearing virtually before the Commons Treasury Committee, he insisted there was “absolutely no wrongdoing” in his lobbying attempts, but accepted that former prime ministers must “act differently”.

Mr Cameron confirmed he was a “regular” attendee of Greensill’s board meetings but said there was “certainly no sense of jeopardy” over the firm’s future as the coronavirus pandemic struck.

Committee chairman Mel Stride questioned whether his “opportunity to make a large amount of money was under threat” as he sent a “barrage” of messages last spring when the pandemic broke.

Mr Cameron replied: “I have spent most of my adult life in public service.

“I believe in it deeply.

“I would never put forward something that I didn’t believe was absolutely in the interests of the public good.

“I did not believe in March or April last year when I was doing this contact there was a risk of Greensill falling over.”

He repeatedly refused to say how much he stood to gain from his involvement with Greensill, saying it is a “private matter”, but he insisted that suggestions he was to make £60 million are “completely absurd”.

“I had a big economic investment in the future of Greensill, so I wanted the business to succeed, I wanted it to grow,” Mr Cameron said.

He said he had shares in the firm and was paid a “generous, big salary” which was “far more” than he made as prime minister, when he earned around £150,000 per year.

Mr Cameron began his role as an adviser to Greensill in August 2018, just over two years after he resigned as prime minister in July 2018.

The firm’s found, Lex Greensill, advised the Government during Mr Cameron’s time in No 10 but he denied he had been offered a role while in office.

“I think I met him twice while I was in Downing Street and I can absolutely confirm at no stage did he ever suggest that I would go and work with him or for him afterwards,” Mr Cameron said.

I think I met him (Lex Greensill) twice while I was in Downing Street and I can absolutely confirm at no stage did he ever suggest that I would go and work with him or for him afterwards

As well as messaging and speaking to Mr Sunak, the former prime minister texted senior Cabinet minister Michael Gove and held a call with Health Secretary Matt Hancock.

Other recipients of Mr Cameron’s texts include Boris Johnson’s senior adviser Sheridan Westlake, Treasury ministers Jesse Norman and John Glen, and deputy Bank of England governor Sir Jon Cunliffe.

He described opposition to Greensill’s access to the Government-backed loans as “nuts” and “bonkers” in his correspondence.

Under questioning from the MPs, Mr Cameron defended approaching ministers and senior Government officials by text as opposed to email in the context of the pandemic, saying it was “a time of extraordinary crisis”.

But he added: “I think, in future, one of the lessons I take away is prime ministers should only ever use letter or email and should restrict themselves far more.”

The extent of his communications was described by Labour’s Dame Angela Eagle as “more like stalking than lobbying” as she asked if he was “at least a little bit embarrassed” about his behaviour.

Mr Cameron responded: “I was keen to get it in front of Government, but as I’ve said, there are lessons to learn and lessons for me to learn and in future the single formal email or formal letter would be appropriate.”

Greensill was placed into administration in March, threatening thousands of UK jobs at Liberty Steel which was dependent on its finance.

The Financial Conduct Authority is formally investigating its collapse, having received allegations that were “potentially criminal in nature”.