The financial services company Greensill Capital collapsed this month, which could trigger the demise of GFG Alliance, a conglomerate owned by Sanjeev Gupta, who owns the third-biggest steel company in Britain.

If Gupta’s Liberty Steel goes under, 5,000 British jobs are at stake.

The former prime minister David Cameron is facing demands to explain his relationship with Greensill Capital’s founder, Lex Greensill, the son of watermelon farmers who was made an adviser to the government in 2014 and appointed a CBE in 2017.

After Cameron left office in the wake of the EU referendum defeat, he became an adviser to Greensill’s company. So far, Cameron has declined to speak on the record about his relationship with Greensill, or his attempts to lobby on his behalf.

The questions that remain unanswered include:

1. Who introduced you to Lex Greensill? Was it your former cabinet secretary Sir Jeremy Heywood? And what role did you play – if any – in providing Greensill with a security pass and access to civil servants when you were in coalition government?

2. Who approached you in 2018 with an offer of a job as an adviser to Greensill Capital? What was the total value of your share options in Greensill?

3. It was claimed in the Times that you told friends you would make $60m from the listing of Greensill. Is this true?

4. It has been widely reported that you texted the chancellor, Rishi Sunak, to lobby on Greensill Capital’s behalf – is this true? Who else in government did you lobby?

5. Did you, as has been reported, ask Sunak to grant hundreds of millions of pounds in taxpayer-funded loans to the company?

6. Lex Greensill claimed that in 2018 you brokered an introduction to Barack Obama that helped him build up his business empire. Did you introduce Greensill to Obama?

7. Did you know how close Greensill Capital’s relationship with Gupta was?

8. Did you know how much money was being loaned out to Gupta’s metals empire, GFG Alliance?

9. Should lobbying rules be tightened in light of the current controversy to include in-house lobbyists such as you when you lobbied on Greensill Capital’s behalf?

10. Do you now regret saying in 2010 that lobbying “is the next big scandal waiting to happen. It’s an issue that crosses party lines and has tainted our politics for too long, an issue that exposes the far too cosy relationship between politics, government, business and money”?