The fundamental problems with his leadership very much remain. The Tories' lead over Labour remains safely in the double digits, with YouGov's latest poll putting it at 17 per cent. The electorate is increasingly showing what this means for Labour at the ballot box.

Yesterday, the Conservatives made in-roads into Middlesborough, taking a council seat in the Coulby Newham ward off Labour after a swing of more than 8 per cent in their favour. This ward shouldn't have been a hard fight, as it tends to elect Labourites to represent it (and an occasional independent). But under Mr Corbyn, it has become eminently contestable by the Tories for the first time.

A council seat may seem like an electoral trifle, but it shouldn't be ignored. Mr Corbyn can get stroppy when Labour's performance in local elections is overlooked. The Conservative campaign machine has been rampaging all over the electoral map lately, with the seizure of the parliamentary seat of Copeland in February being its biggest coup this year.

Labour tried to shrug it off as a mere "hiccup", but it will have to brace itself for further electoral pain at next month's local council elections, when experts expect them to lose scores of seats to the Tories.