The PM only had to look at the Labour leader to realise that life could be a lot worse

Things may look bleak for Jeremy Corbyn, but he still has one MP he can count on. As the Labour leader entered the Commons, Dennis Skinner – the octogenarian stalwart of Old Labour – leapt from his seat, strode across the floor, and, in front of the entire Parliamentary Labour Party, shook him warmly by the hand. It was a touching moment of fellow feeling and kindness.

Or at least, it would have been, if Mr Skinner hadn’t then turned, glared at the former members of Mr Corbyn’s shadow cabinet, and flicked a V-sign at them. We knew the EU referendum battle would damage the Tories. We didn’t know it would shatter Labour.

The House of Commons was sitting for the first time since the country voted for Brexit. Despite the internecine warfare of recent months, Tory MPs from both sides of the campaign seemed remarkably chipper. Perhaps they were just enjoying the turmoil of the shadow cabinet resignations. Before discussion of Brexit could get under way, a new MP for Labour had to be sworn in: Rosena Allin-Khan, Sadiq Khan’s successor in Tooting. “Give her a job!” hooted a Tory backbencher at Mr Corbyn.

The Labour leader did not look amused. Probably because at this rate he might have to.

By contrast, David Cameron – who on his arrival was cheered to the rafters by Tory MPs – seemed almost breezy. Three days earlier, a broken-looking Prime Minister had announced his resignation alongside his tearful wife; yet now he was calm, generous and good-humoured. Defeat, it appeared, hadn’t crushed him – if anything, it had released him.

Mr Cameron reminded the Commons that the process of extricating Britain from the EU would be a job for the next prime minister. “Where is he?” shouted voices from the SNP and Labour. Boris Johnson, as it happened, was absent. Michael Gove lurked behind the Speaker’s Chair.

Mr Corbyn, meanwhile, was still clinging grimly to the misery of office.

Remarkably, he even used his remarks on the EU to scold his Labour opponents. “Our country is divided,” he snapped, “and will thank neither the benches in front of me – nor those

behind– for indulging in internal,

Hilary Benn was called to ask a question on Brexit. Labour MPs cheered him. Mr Corbyn ignored them

factional manoeuvring at this time!” “Resign!” shouted MPs. And not all of them were Tory. Yes, we really were watching a Labour leader and his own MPs lay into each other in public.

I glanced at the back benches. Chris Bryant – until Sunday, the shadow leader of the House – sucked in his cheeks tartly. Hilary Benn – until Sunday, the shadow foreign secretary – folded his arms and sniffed.

In due course, Mr Benn was called to ask a question on Brexit. Labour MPs cheered him lustily. Mr Corbyn ignored them and scribbled crossly in his notepad. When he himself had been called, his MPs sat in glowering silence.

Mr Cameron seems happier for having given up his job. I wonder if Mr Corbyn noticed.