LABOUR suffered an epic and emphatic defeat at the general election because it had the wrong leader and the wrong approach, according to former Darlington MP and Cabinet minister Alan Milburn.

In a brutal assessment of Ed Miliband's leadership, the social mobility tsar, who was born in Tow Law, said the party "could not have got it more wrong" in its fight for No 10.

Labour attempted to defy the laws of political gravity as it pitched further to the left and ended up driving voters into the arms of the Conservatives, he claimed.

In a speech to the Centre for Social Justice think tank, Mr Milburn warned that the party must come to terms with the New Labour era and Tony Blair's leadership.

Mr Blair is one of Britain's "great" leaders and attempts by Gordon Brown and Mr Miliband to distance themselves from his premiership only persuaded voters that old Labour was back.

A leading figure in the New Labour era, Mr Milburn also gave his backing to Liz Kendall in the Labour leadership contest.

He said: "On issue after issue, Labour tried to defy the laws of political gravity.

"Labour gambled we could win despite trailing the Conservatives both on political leadership and economic competence.

"We had the wrong leader and we had the wrong approach.

"Inevitably, we paid the price.

"We could not have got it more wrong.

"We decided to ditch rather than defend the Labour government's record, leaving our opponents with an open goal."

He added: "There was no great appetite for the Conservatives in the country but we drove voters into their arms."

The "foolish revisionism" of party figures who turned their backs on Labour's winning formula have "sunk" the party, he said.

He added: "Political parties have to exist for a purpose and so do party leaders.

"Without it they are nothing.

"Great leaders always have a big purpose.

"For Churchill it was victory in war, for Thatcher victory against a stifling state.

"For Blair it was victory against old-fashioned attitudes and institutions that held our country back.

"Today, to be blunt, voters are no longer sure what Labour is for.

"They do not see a compelling core purpose."

It comes as Labour launched a concerted push to rebuild relations with business in the wake of the party's shattering general election defeat.

Shadow chancellor Chris Leslie and shadow business secretary Chuka Umunna will spend the summer touring firms around the country in a new charm campaign which recalls Labour's "prawn cocktail offensive" to win over business leaders in the 1990s.

The move will be seen as a recognition that its relations with business plunged to a low ebb under Mr Miliband who was accused of failing to understand the world of commerce.

A series of damaging clashes with leading business figures - some of whom who had previously supported the party - were played out in the run-up to the election.

Mr Leslie said: "The disappointing election result for Labour rightly forces us to rethink how we build stronger relationships with the business community."

Meanwhile, polling has found Andy Burnham is the leadership contender judged most likely to improve the party's chances at the next general election.

A survey of 2,000 people by ORB for The Independent found more than one-in-three - 36 per cent - believed the shadow health secretary was Labour's best prospect for the 2020 general election.

Liz Kendall, the Blairite shadow care minister, was second with 25 per cent followed by shadow home secretary Yvette Cooper on 20 per cent, just two points ahead of left winger Jeremy Corbyn on 18 per cent.