There was relief for Tories when they defended a marginal seat in the latest council by-elections after slumping in some other contests since the May 2 main polls.
They held on at Fazeley, Lichfield District, Staffordshire by 48 votes.
In the 2011 elections Labour won one of the other two seats in the ward which comes under the marginal Tamworth parliamentary constituency.
Tories fare much worse in a calculation based on a relatively small sample of seven comparable by-elections since May 2.
This suggests a projected 14.2% nationwide Labour lead over Conservatives.
A calculation based on four wards fought both times by all three major parties gives a line-up of: Lab 49.6%, C 27.9%, Lib Dem 7.5%.
It is not possible to include a projected figure for Ukip as there is not sufficient data yet from past elections.
Its average vote share in the five wards it contested is 29.1% compared with 23% in a BBC survey of the main polls
In only one of the by-elections - at Barking and Dagenham, east London - did it stand a candidate both times. Its vote share there rose by 13.5% compared with the previous poll on the same day as the 2010 general election.
Lichfield District - Fazeley: C 423, Lab 375. (May 2011 - C 758, 595, Lab 512, C 460). C hold. Swing 1.1% C to Lab.