David Cameron has defended his lobbying of UK ministers and officials on behalf of Greensill Capital, insisting it was to benefit the economy rather than preserve the value of his share options in the company.

The former prime minister, giving his first public comments about Greensill since it collapsed in March, refused to say how much money he was on track to earn from the supply-chain finance company before it went into administration.

Industry figures have told the Financial Times that Cameron had shares worth close to 1 per cent of the value of Greensill. The company was at one point valued at $7bn.

But Cameron told the House of Commons Treasury select committee that suggestions of a potential windfall for him from Greensill were “completely absurd”. He declined to say what the actual figure was but said he had share options and was paid a “generous amount, far more than I earned as prime minister”.

He added that he had a “big economic investment in the future of Greensill”.

Cameron lobbied several ministers and civil servants including Treasury officials on 56 separate occasions in an attempt to secure Greensill’s access to two government-run Covid-19 debt schemes.

After three months of talks, the Treasury decided in mid-2020 that it was not interested in Cameron’s proposals.

Mel Stride, Conservative chair of the Treasury committee, said Cameron could have been motivated to “undertake this barrage” of contacts at the start of the coronavirus crisis in the spring of 2020 because he had realised his “opportunity to make a large amount of money was under threat”.

The former prime minister said: “My motivation for contacting the government was we had a really good idea for extending credit to businesses.”

Stride asked whether Cameron should have known Greensill was in trouble when concerns first emerged about the firm, including in a May 2020 Financial Times report.

But Cameron said he did not realise the company was in serious difficulty until December 2020. “I did not believe in March or April [2020] . . . there was a risk in Greensill falling over.”

Angela Eagle, a Labour member of the committee, told Cameron some of his messages to ministers and officials seemed “more like stalking than lobbying”.

But Cameron defended his lobbying, saying that Treasury officials did not think it was “inappropriate” given the “economic heart attack” happening to the UK at the start of the Covid-19 pandemic.

The reason for his “persistence” was that financial technology companies such as Greensill were “not well understood” by most people, he added.

Cameron confirmed that he regularly attended Greensill board meetings despite his not being a director of the company, nor involved in the day-to-day running of the business.

“I would take part in the board meetings, listen to the arguments, make contributions, particularly on geopolitical matters,” he told MPs. “I didn’t sit on the credit committee, risk committee or audit committee.”

Cameron also tried to win clients for Greensill and helped with relationships with important clients.

Greensill’s path to collapse began in September 2020 when Tokio Marine, its main insurer, gave notice that it was withdrawing cover within six months.

Cameron said he had not been aware of the move, even though he had been attending board meetings and listening to the company’s internal podcast.

The former prime minister acknowledged Greensill had an excessive “client concentration” with GFG, the metals group run by the industrialist Sanjeev Gupta.

He also said it was “very disturbing” to read an FT report that companies listed on Gupta loan documents denied doing business with GFG.

But Cameron defended Greensill’s practices. “Just because the business goes into administration, it doesn’t mean that everything about it was wrong,” he said. “It doesn’t mean the whole thing was some giant fraud.”

Cameron said that as prime minister he had drawn up rules requiring the disclosure of any meetings between ministers and lobbyists — but not of texts and phone calls.

In opening remarks to the committee, Cameron said he had not breached the rules, but he admitted that “prime ministers are in a different category” in terms of conduct after leaving office.

As such he had made a mistake by lobbying ministers and officials by text message rather than writing a formal letter, he said.

Cameron said it was “very depressing” to have worked for a failed company.

He later told the Commons public accounts committee that it was former cabinet secretary Jeremy Heywood who brought Greensill into Whitehall in 2011 to advise the government on supply-chain finance — which led to the creation of a loan scheme for pharmacies.

He said he only met Lex Greensill, the company’s founder, twice before 2016 and that he had no role in Greensill Capital’s being awarded the pharmacy contract in 2018. “That’s like saying, I’ve benefited from arranging your marriage six years ago because six years later I’ve married your ex-partner.”