There is no reasonable definition of "the Left" that includes the British Labour party. The only one that fits would be "to the left of the British Conservative party", but that's as arbitrary as redefining it "to the left of Reform UK" and then starting to call the tories "The Left".
> There is no reasonable definition of "the Left" that includes the British Labour party.
https://en.wikipedia.org/wiki/Labour_Party_(UK)
> Labour, is one of the two main political parties in the United Kingdom, along with the Conservative Party. It sits on the centre-left of the left–right political spectrum