"We all know how it works. The lunches, the hospitality, the quiet word in your ear, the ex-ministers and ex-advisers for hire, helping big business find the right way to get its way," so said Mr David Cameron in 2010, in a speech on lobbying shortly before he became prime minister.

A decade on, it has become painfully clear that the former leader did indeed know how it worked. In recent weeks, Mr Cameron has seen his reputation savaged amid details of his lobbying efforts on behalf of financier Lex Greensill. Each day has brought new revelations about the relationship between the government and Greensill Capital, the supply chain finance company which collapsed last month.