Defection ends conference.
Cllr Lynnie Hinnigan (nee Williams), who represents the Mossley Hill ward on Liverpool Council, joined Labour live on stage at the closing of the conference at Liverpool's Echo Arena yesterday.
She said she could no longer stay in a Lib-Dem party which was part of a coalition Government delivering huge public sector cuts to the city.
Cllr Hinnigan insisted she would not be standing for re-election in May and wanted to get to know the Labour party before she put herself forward for public office again.
After a standing ovation from the conference, she said: "Nick Clegg lied. He lied to me and he lied to the people of Liverpool.
"I am not a career politician and I will not stand for election in May. I am not doing this because I wanted to cross the floor to get a safer seat.
"I wanted to do what was right for my children, my stepchildren and my city."
She later said she would be now be able to sleep easier at night.
The manner of her defection drew immediate anger from Liberal Democrat leader Paula Keaveney, who said Cllr Hinnigan had not given her the courtesy of a warning message.
The defection means Labour now have 63 of 90 seats on the city council.
But some in the party are concerned it has been too quick to accept defectors.
Cllr Hinnigan joins former Lib-Dem Cllrs Gary Millar and Ian Jobling, and ex-Conservative Steve Fitzsimmons, who have all joined the party since Labour took control of the town hall in May last year.
Cllr Keaveney said: "It was the height of rudeness not to give her former colleagues a small amount of notice.
"I would have expected better. I was the person who signed Lynnie up to the Liberal Democrats, so it is disappointing. "She clearly decided to do it in this way because it would cause the most damage.
"People have to live with their own consciences about the way they behave."
Cllr Lynnie Hinnigan takes to the podium after defecting