By Andrew MacAskill, Elizabeth Piper and Alistair Smout LONDON (Reuters) -British Prime Minister Keir Starmer won a vote on his welfare plans on Tuesday but it came with a significant political cost as he suffered the biggest parliamentary rebellion of his premiership and backed down on key elements of the package to secure the bill's passage.

British Prime Minister Keir Starmer marks a year in office this week, facing challenges from within his party and the public.

Keir Starmer faces crunch vote on welfare spending after watering down planned cuts to disability benefits. The United Kingdom’s Labour government hopes to limit a rebellion over welfare reform from its own politicians in a key vote in Parliament, just days after attempting to win them over with concessions.