Sam Hall of the Conservative Environment Network urged the government to rethink its stance on environmental issues, arguing Ministers should be doing more to promote their achievements on an agenda that remains popular with the public.
"These are very disappointing by-election results for Conservatives," he wrote on X. "While there is no evidence that the Prime Minister's recent changes to net zero policies have caused the defeats, it is clear that they haven't prevented them.
"Nor have they motivated 2019 Conservative voters to turn out in sufficient numbers. The party needs to reappraise the lessons it drew from the Uxbridge by-election, which was in truth a specific rejection of ULEZ expansion rather than environmental policy more broadly.
"The environment is one of the greatest areas of achievement of Conservative governments since 2010. It's not too late to build on this by taking bold steps on climate change and nature now and by setting out a positive vision for the environment at the next election."