By Andrew MacAskill, Elizabeth Piper and Alistair Smout LONDON (Reuters) -British Prime Minister Keir Starmer won a vote on his welfare plans on Tuesday at significant political cost as he suffered the biggest parliamentary rebellion of his premiership and was forced to back down on key parts of the package.

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

However, t here are doubts over whether the bill, in its current form, will make any significant savings, after a series of government concessions. Prime Minister Keir Starmer was forced to abandon a key plank of his welfare reform package in the face of a Labour rebellion, which would have led to a Commons defeat.