liam byrne , who was chief secretary to the treasury under gordon brown , left a memo on his desk after labour 's election defeat in 2010 .
the note has become emblematic of labour 's fiscal irresponsibility in office and was used by mr cameron in the seven-way leaders ' debate earlier this month .
when the coalition took office in 2010 the budget deficit had reached more than £ 150billion .
more than 10 per cent of the entire size of the economy .