Lib Dems would win Chelmsford on much less than Bromley swing

The 14% swing from Conservatives to Lib Dems in the Bromley by-election on 29 June is more than double what the Lib Dems need to win the Chelmsford constituency. The drop in the Conservative majority of 11% is the worst by-election result for the Conservatives in a Tory seat since Wirral South in February 1997 - the last days of the John Major premiership.
The result was equally bad for Labour, with a Labour to Lib Dem swing of 17% and slumping into fourth place.
The major Lib Dem success in Bromley on 29 June was assisted by Liberal Democrats from Chelmsford, who helped deliver large quantities of leaflets.