According to James Forsyth:
Khalid Mahmood has resigned from the Labour front bench saying that 'A London-based bourgeoisie, with the support of brigades of woke social media warriors, has effectively captured the party' source
This comes after the historic election loss for Labour in local elections, where the party bled even more in working-class areas than it did in 2019.
Why didn't you tell us before you quit Labor.
Haven't looked deeper, but "quitting the labour front bench" doesn't mean leaving labour, it means becoming "a back bencher", still presumably doing the work of an MP but no longer being part of the "front rank" or the shadow cabinet etc, or something along those lines. I forget the specifics off the top of my head.
Back benchers retain party affiliation, but are less directly under the control of whoever is nominally in charge of the party at the time, and are much more free to vote against party line, etc.
He probably believed that it could be wrestled back from them once Corbyn was kicked out. But it's now clear that that isn't going to happen any time soon.
The party is basicaly dead outside the M25 and a thin sliver of the most urbanised areas of the north.