John Healey dragged into scandal as Labour attacked lobbying politicians He urged Treasury to give Greensill £200million in taxpayers' Covid-19 loans Mr Healey says his intervention was right because of steel works in constituency Lex Greensill reassured staff in a video on February 15 of 'strength' of funds Two weeks' later Credit Suisse froze the funds, leading to Greensill's collapse Ex-PM David Cameron is facing questions over his closeness to the tycoon