By Ashley Cowburn David Cameron has repeatedly refused to say how much he earned from his work for failed firm Greensill Capital after stepping down as Prime Minister. The ex-PM said he didn’t have to disclose his earnings because he was a “private citizen” at the time – despite being asked three times on the BBC’s Sunday with Laura Kuenssberg. Lord Cameron had sought access to an emergency Covid loan for Greensill Capital, which was headed by ex-No10 adviser and banker Lex Greensill. The firm collapsed in March 2021 and the same year a report by MPs accused the ex-PM of a “significant lack of…