THE prospect of a progressive alliance between Labour and the SNP at Westminster on issues like scrapping Trident and Lords reform has been talked up by the Nationalist leadership as Jeremy Corbyn finalised his frontbench team.

Stewart Hosie, the deputy SNP leader, was asked, given the similarities between his party and Mr Corbyn’s on certain policies, if there was room for co-operation.

“Yes, absolutely,” declared the Dundee MP.

“We think Jeremy Corbyn has probably voted with the SNP more than any other Labour MP. He is now the leader, so here’s a challenge; if he can bring his party with him on the things he believes in of which many, not all by any manner of means, but many are the same as ours, perhaps we can have the opportunity of a genuine progressive alliance that we spoke about at the election.

“So if, for example, we can have Labour rolling in behind to say No to Trident and its replacement, if we can Labour rolling in behind to say let’s properly reform the House of Lords, no more unelected peers, that would be a great result. But, of course, he has the challenge to bring with him many people, a number of whom have said they won’t serve under him.”

Mr Corbyn – due to visit Scotland later this week - was ensconced at Labour’s HQ yesterday, having private conversations with colleagues about the make-up of his Shadow Cabinet, which is, according to senior party sources, due to be announced later today.

Shadow Northern Ireland secretary Ivan Lewis was the first confirmed casualty as he tweeted that he was to replaced.

Rosie Winterton is set to remain as Chief Whip, while Emily Thornberry, a former Shadow Attorney General, is expected to be offered a high profile role; she said people had a “duty” to serve in the interests of party unity. Angela Eagle, a former Treasury Minister, is tipped for the Shadow Chancellorship.

Ian Murray, as the only Labour MP in Scotland, seems assured to continue as the Shadow Scottish Secretary, while Hilary Benn was expected to remain as Shadow Foreign Secretary but there was a rumour the job might be offered to Andy Burnham, Mr Corbyn’s leadership rival, and currently Shadow Health Secretary.

Tom Watson, the new deputy leader, made clear his leftwing colleague was putting together a "broad-based" Shadow Cabinet.

“He wants a frontbench that represents all the talents and all the views. So I say to colleagues: watch this space, respect the mandate he has been given from our members, try to unify and let's try and get an exciting programme for 2020.”

However, a number of high-profile Labour figures have made clear they will not serve in Mr Corbyn’s team; these include his leadership rivals Yvette Cooper and Liz Kendall as well as Chris Leslie and Tristram Hunt, the Shadow Chancellor and Shadow Education Secretary respectively.

Sir Paul Kenny, General Secretary of the GMB, said while he understood why some people could not bring themselves to serve under Mr Corbyn, he warned against sniping from the sidelines.

“Frankly, if they are going to spend the rest of whatever time it is constantly sniping, talking about rumours of leaving, then the best thing they can do is go. Go off into the oblivion [like] previous splitters from the Labour Party have done.”

In a sign of potentially divisive battles to come, Mr Watson - seen as a crucial linchpin in securing party unity - accepted that he and many other MPs backed the renewal of Trident, something Mr Corbyn is deeply opposed to.

He claimed there was no "massive disagreement" on Nato membership – the West Bromwich MP is in favour of UK membership while the Islington MP is opposed - but conceded he didn't know "precisely what Jeremy's position" was and hoped to "convince him of the merits" of Britain's membership.

Tory HQ seized on the deputy leader’s comments, saying they showed the Labour leadership was “deeply divided on key national issues”, which showed the party was a risk to Britain’s security.

Earlier, Michael Gove, the Justice Secretary, said the Tories should not be "gleeful" at Mr Corbyn’s election but "face up to that reality" that he could become prime minister.

"It is because of that that we have to lay out at this time the scale of the risk that would be posed to Britain.”

Matthew Hancock, the Cabinet Office Minister, said the London MP’s election was a “dangerous moment” for Britain as he was one of Westminster’s most left-wing MPs whose policies harked back to the past. “His policies would be a disaster for our country,” he added.

At the TUC conference in Brighton, there was nothing but delight and support for Mr Corbyn’s victory.

Dave Prentis, the Unison General Secretary, summed up the mood when he said the leftwinger’s triumph would "bring about nothing but good” for Labour.

"We have been through a terrible defeat but this overwhelming result will rekindle hope...It will give us the opportunity to have a new kind of politics and win the next election".

Mr Corbyn is due to address the TUC conference tomorrow when he can expect a rapturous welcome.