Tristram Hunt's resignation is sudden but hardly unexpected. Bright, young and ambitious, the historian entered politics with the hope of becoming a cabinet minister. But Labour has never been further from power. His party is led by Jeremy Corbyn, to whom he is implacably opposed, and his Stoke seat is due to be abolished in the boundary changes (posing the prospect of a tricky selection contest). In these circumstances, only a masochist would have declined the chance to become director of the V&A.

Hunt's announcement follows that of Jamie Reed, who is resigning his Copeland seat to become Head of Development and Community Relations for Sellafield power station. Labour MPs believe that many more will follow. The party's parlous poll ratings, Jeremy Corbyn's re-election (in defiance of 80 per cent of MPs), the boundary review (the first since 2010) and opportunities outside parliament all mean that Westminster is an increasingly unattractive berth.

Under the boundary changes, some Labour MPs will see their seats become notionally Conservative. As UK Polling Report's Anthony Wells has calculated, Andy Slaughter will face a Tory majority of 14 per cent in the new Hammersmith and Fulham seat, Gareth Thomas will face one of 11 per cent in the new Harrow and Stanmore seat, Ruth Cadbury will face one of 10 per cent Brentford and Chiswick and Tulip Siddiq will face one of 9 per cent in Hampstead and Golders Green. Alison McGovern and Margaret Greenwood are both eligible to seek selection for the new Bebington and Heswall seat but it is also notionally Tory.

Labour MPs whose seats would be vulnerable based on current poll ratings include Rupa Huq (274 majority), Wes Streeting (589), John Woodcock (795), Karen Buck (1,977), Tom Blenkinsop (2,268), Mary Creagh (2,613), Gisela Stuart (2,706), Kerry McCarthy (3,980) and Ian Austin (4,181). "There's not a safe seat north of Islington," an MP told me recently. Others, such as Stella Creasy and Peter Kyle, are at risk of deselection by local activists (through the trigger ballot mechanism).

Then there are those already seeking lifeboats. Andy Burnham and Steve Rotheram are bidding to become the mayors of Greater Manchester and Liverpool respectively. Brexit will create new opportunities for those with political and European expertise as businesses seek to equip themselves for the upheaval.

Labour has already suffered a severe brain drain at adviser level. It is now facing one of its MPs.