In his keynote address, the Chancellor sought to draw a stark distinction between the 12 years’ experience he and Gordon Brown had in office with the youthful inexperience of the Conservative leader and George Osborne, his Tory shadow, whom he insisted had contributed ­“little that is grown-up” to the economic debate.

Mr Darling declared: “That will be the choice in the next few months: maturity and experience against the politics of the playground; investment in the future against a return to the past.”

In a speech with few rhetorical flourishes, the Chancellor also warned bankers that there could be “no return to business as usual” after the recession with legislation planned to end automatic bonuses and curb the reckless pursuit of short-term profits.

However, just days after suggesting Labour appeared to have “no fire in our bellies”, he directed his fire mostly at the Tories, accusing Mr Cameron and Mr Osborne of getting every major decision wrong on the recession.

He evoked the memory of the Thatcher and Major governments, which he argued, had left “a legacy of disdain, underinvestment and shaming poverty”, and he warned that a return to Tory rule would again inflict damage on the fabric of the nation.

Mr Darling branded the Conservative approach “wrong, naive and downright dangerous”, saying Tory plans for faster and deeper spending cuts would damage the economy and endanger the fragile recovery; what was needed was sustained investment to maintain frontline services.

“If we followed the Tory route now, recovery would be put at risk, prospects for growth damaged, borrowing would be greater.”

He added: “We cannot and must not let that happen. And we cannot, must not, repeat their mistakes of the 1980s and 1990s when short-term job loss became long-term unemployment for a whole generation.”

However, the Chancellor acknowledged cuts were inevitable following the election.

“To get borrowing down, spending will have to be tighter in the years ahead, against a background where public investment has tripled over the past decade.”

Yet he stressed: “Tighter spending doesn’t mean a return to the Tory dark ages. It does mean a determination to cut waste, cut costs and cut lower-priority budgets.”

He added: “This will require difficult decisions. I haven’t shirked them in the past, I won’t shirk them now.”