A Brent Liberal Democrat councillor has defected to Labour, claiming his local party leader’s “posturing” on library closures was “an insult” to campaigners.

Councillor James Allie, who represents Alperton, announced his switch to Labour in an open letter released this morning, in which he listed a series of damning criticisms of both Lib Dem MPs in Westminster and his former colleagues in Brent.

He said he had been “sickened by the hypocritical things the Liberal Democrats do and say here in Brent”, and that the party had “betrayed the values” he once shared with them.

He wrote: “The people I represent in Alperton are struggling more than ever under this government, but the Liberal Democrat leadership in Westminster is prioritising reform of the House of Lords instead of a plan for economic growth.

“The closure of the accident and emergency at Central Middlesex Hospital under this Government is an astonishing betrayal. Brent MP Sarah Teather campaigned to keep the A&E when it was not under threat of closure. Now she is in government closing it. I am only sorry that I trusted her back then and I am sure that a number of her constituents feel the same way.

“The leader of the Liberal Democrats in Brent, Paul Lorber, also knows very well that had the Lib Dems won the local election in 2010 they would have faced the same pressure to close the six libraries in Brent that have caused such a stir. It is the coalition’s cuts to local government that have caused this problem and Cllr Lorber’s posturing on the issue is just an insult to the library campaigners and the people of Brent.”

Plans were put forward last month by NHS North West London to close the department at Central Middlesex and downgrade the hospital, which campaigners believe would put further strain on Northwick Park Hospital’s facilities.

Ms Teather last month called on the body to halt the plans and give residents a better chance to have their say, but declined to condemn the proposals to close the £62m department which was only opened six years ago.

Cllr Lorber campaigned against the closure of Barham Park Library, which was open for 60 years in Harrow Road, when it was one of six closed by Brent Council last year, and has supported a new pop-up library run by activists in Barham Primary School.

The council said that the move would save £1million a year but would also improve the service at the six remaining libraries.

Cllr Allie’s defection to Labour means their majority in the council chamber goes up by one to 25, with 41 councillors compared to the Lib Dems’ 16.