It was 9.30pm on Sunday night when Norwich South MP Clive Lewis was called by the leadership to see if he would take on the key role of shadow defence secretary. He was at Glastonbury Festival when Jeremy Corbyn turned to him to fill the post after a string of resignations threw his party into chaos on Sunday. He knew he wouldn't make it back for the monthly chance to hold the defence secretary to account in the House of Commons question time.

The chaos has deepened since then with Labour MPs agreeing a vote of no confidence in Mr Corbyn and with a leadership election now on the cards.

Asked what he planned to do in his new role, Mr Lewis wryly remarked 'survive'.

'In many ways I don't know whether I will be in the job in a few months time. It is highly unlikely,' he said.

But while he is in post he has a busy schedule. He will be representing his party in a debate on Battle of the Somme commemorations today, and the actual events on Friday.

And more generally there is the controversial national policy forum review addressing the tricky issue of Labour's nuclear weapon policy.

But foremost in his mind will be the implications of Thursday's vote by the British people to leave the European Union.

He said there would be implications for the defence industry, for jobs, for research, for procurement.

'There are the implications of the destabilisation of Europe. We don't know yet how that will pan out. The implications of that on the European strategic situation. There are so many things that have a knock on effect. They are so many things I will have to start thinking about for our country's defence.'

All this is happening in the context of a bloody internal fight after former shadow business secretary Angela Eagle is set to challenge Jeremy Corbyn for the leadership after a vote of no confidence.

Mr Lewis says the rebel MPs – of which there are many – have misjudged Jeremy Corbyn, assuming that he would resign in the wake of a no confidence vote.

He describes the situation as the 'worst of all possible worlds', with the party set to fight a 'bitter protracted leadership contest at a critical juncture in our country's history'.

'We will be inward looking and the Tories will be getting through what they are doing as quickly as possible at a time when we could be leading the debate about the future direction of our country.'

'I think everyone knew the unity of the Labour Party was always quite shallow, I think at this critical juncture it feels irresponsible. All I see is that whoever wins this contest, will inherit a smoking demoralised divided party. To say there is only one option – that Jeremy resigns – is to say, in effect, 100 MPs are telling however many hundred thousand members that they know better. Where in a democratic dialogue or system does that make sense?,' he added.