He has announced his decision in an article for Huffngton Post:
No one has to remain a member of Labour, should you disagree with the path the party is taking any member has the right to stop their support. Many decent Labour members did just that under Tony Blair, many others will take the same decision now.
The time, for me at least, to stop supporting the party has come with the re-election of Jeremy Corbyn.
I’ve never disliked Jeremy Corbyn, and although I deeply dislike some of the company that he keeps he seems a personable guy, but I firmly do not agree with the direction that he has taken Labour.
I don’t like Jeremy’s approach to public services where dogma seems far more important than solutions, I don’t like his approach to defence or Britain’s position in the world, I don’t for one second believe he understands what motivates ordinary, hardworking people in communities like mine.
I can’t ever see Jeremy as a Prime Minister leading our country in tough negotiations or at times of threat.I wish all the people leaving Labour well, whether they decide to join the Liberal Democrats or not.
It must be an awful wrench to leave a party that has been an important part of your identity.