Jeremy Corbyn new Labour leader
John Mills spoke to IBTimes UK after Jeremy Corbyn secured a 'resounding' victory Getty

A top Labour donor and campaigner has called on upset party members to "stick around" after Jeremy Corbyn triggered an earthquake under Westminster by winning the Labour leadership election. John Mills told IBTimes UK that the left-winger's victory was "resounding" and called for unity, despite disagreeing with Corbyn on major policy areas.

"I would say stick around," said Mills. "The thing to do is not to take umbrage and say, 'Oh, because someone has been elected where you don't agree with everything he says, we have to de-camp and join some other party.' I want to stay in the Labour Party, keep on working for the sort of policies which I think will work best and are most likely to get Labour elected," the businessman said.

But Mills, the founder of JML who has given Labour £1.5m ($2.3m) and is chairman of campaign group Labour for Britain, said: "I'm not sure that Corbyn shares my view on what needs to be done to get away from austerity. The only way you can possibly get away from austerity is to grow the economy much more quickly.

"But the sort of policies that the far-left tends to go for don't unfortunately lend themselves very easily to getting the rate of economic growth up: you've got to get business on side, you've got to increase profitability – these aren't part of the far-left agenda."

Labour leadership: Watch the moment Jeremy Corbyn is elected Labour leaderIBTimes UK

The comments come after Labour announced on 12 September that Corbyn had secured a 60% share (251,417 votes) in the party's leadership election, easily beating his centre-left and Blairite rivals Andy Burnham (19%), Yvette Cooper (17%) and Liz Kendall (4.5%).

The rebel backbencher was a relative unknown beyond Westminster before the contest, but his shock frontrunner status in the contest catapulted the 66-year-old into the national limelight. The veteran parliamentarian, who is expected to take Labour leftwards, will now have to face David Cameron at Prime Minister's Questions and attempt to rebuild the reds ahead of the 2020 general election.

"We go forward now as a movement and a party, bigger than we have ever been for a very, very long time; stronger than we have been for a very, very long time; more determined than we have been for a very, very long time – to show to everyone that the objectives of our party are intact," Corbyn declared during his acceptance speech at the QEII Conference Centre in London.

The event also saw the election of Tom Watson as the new deputy leader of Labour. The West Bromwich East MP secured 50.7% of the vote in the third round to beat Stella Creasy, the MP for Walthamstow.