Labour crashed to one of its biggest by-election defeats of the Blair era as Liberal Democrats snatched its traditional Nottinghamshire CC stronghold of Sutton-in-Ashfield North.
The swing since May 2005 – on the same day as the general election – was a staggering 43.9%.
But the overall trend for the party over March showed widespread variations, giving it hope of holding the line in some areas in the main 3 May contests.
It gained from Liberal Democrats at Speke-Garston in their Liverpool City powerbase, and won from independent at St Cattwg, Caerphilly CBC, South Wales.
But its biggest boost came at another Welsh contest, when it defended a marginal Treorchy seat on a 9.5% swing at Rhondda Cynon Taf CBC.
The result was a blow for Plaid Cymru ahead of next month's assembly polls.
Lib Dems narrowly captured a marginal Tory Pilgrims Hatch seat at  Brentwood BC, but Conservatives held on at Rooksdown, Basingstoke and Deane BC, defending the overall control of the authority they gained in December.
Last month:
Tories kept control of Basingstoke and Deane BC
Tories defended seats at Basingstoke and Deane BC, Buckinghamshire CC and Northamptonshire CCl Labour gained from Liberal Democrats at Liverpool City and from independent at Caerphilly CBC, and held a Rhondda Cynon Taf CBC seat.
Liberal Democrats gained from Tory at Brentwood BC, and from Labour at Nottinghamshire CC. They held an Elmbridge BC seat.

Independent defended a Powys CC seat.
So far this year, Liberal Democrats have a two-seat net gain in by-elections. Labour has lost one overall and Plaid Cymru one.