Claire Ainsley, a former policy director for Mr. Starmer, said the results also reflected longer-term trends, including a breakdown of traditional class loyalties among voters, the increasing pull of nationalist politics and growing support for the centrist Liberal Democrats, the Greens and independent candidates.
“We have been seeing the fragmentation of society and that has flowed through to our politics,” said Ms. Ainsley, who now works in Britain for the Progressive Policy Institute, a Washington-based research institute. “There is multiparty voting now.”
The upshot is that both main parties are struggling as they find themselves competing not just with each other, but also with opponents to their political left and right.
