The average pundit’s view has been the election of Sir Keir signalled a change in attitude by Labour’s membership away from ideology and towards electability. Left-wingers will therefore be disappointed to see YouGov’s polling today, which shows Boris’s lead on ‘best PM’ has plunged, err, 3% in Keir’s first three weeks as leader – remaining 27% ahead of Sir Keir. Amongst Labour members, Boris has risen from 6% to 8%, with one third not sure.  Starmer’s bounce is weak…