The new leader is already facing a backlash within Labour ranks after appointing one of his most hardline left-wing allies as shadow chancellor.
Serial rebel John McDonnell has been handed the crucial task of overseeing the party’s economic policy in a team that Corbyn’s aides described as “refreshing” and “dynamic”.
Former leadership rival Andy Burnham has accepted a job as shadow home secretary, although a host of significant players have refused to take on front-bench roles. There has also been criticism that no women are in the most senior positions.
McDonnell dismissed claims that women had been snubbed for the top jobs and insisted the health and education portfolios — which have gone to Heidi Alexander and Lucy Powell — are more important than the great offices of state.
He said: “For most people, the real top jobs are the ones that provide the services like health and education, those sorts of things,” he said. “So he has broken with that tradition and I’m really pleased.”
The scale of the problems Corbyn faces in uniting the party were underlined as Hilary Benn, who is staying on a shadow foreign secretary, declined to fully endorse McDonnell’s appointment.
The new shadow leader of the House of Commons, Chris Bryant, revealed he had turned down the defence portfolio because of “profound” disagreements with Corbyn on policy.
Asked if he was 100% behind McDonnell gettng the key economic job, Benn told BBC Radio 4’s Today programme: “This is the choice that Jeremy has made. I respect the choice that Jeremy has made as leader.
“We have just come off the back of two bad election defeats for the Labour Party, and our principle task is to win the people’s trust when it comes to the economy.
“John’s first and last task as shadow chancellor will be to win the trust and confidence of the British people in arguing for a different economic policy.”
Pressed on whether he welcomes McDonnell taking charge of the Treasury brief, Benn said: “I welcome anyone serving in Jeremy’s cabinet... because Jeremy won a thumping victory, we have a responsibility to rally round him.”
Benn tried to calm fears among many Labour MPs that Corbyn could campaign for Britain to leave the EU in the in/out referendum expected next year.
Chuka Umunna stood down as shadow business secretary, complaining the new leader had refused to give him an assurance he would not back a ‘Brexit’.