Let me put my cards on the table. In the Labour leadership contest I am supporting John McDonnell for the reasons outlined here. But, unlike many of the contributors to this discussion, I think Diane Abbott's surprise entry into the leadership race is a good thing.
McDonnell is politically sound and will, in the socialist future, be regarded as one of the finest Labour MPs ever to have sat. But which ever way you look at it even with the deadline for nominating candidates extended to June 9th, McDonnell will find it difficult to get the 32 other MPs necessary to get himself on the ballot paper. However, I would be very surprised if Abbott does not.
I'm a firm believer in the left taking opportunities where they find them. So forget about the less-than-consistent voting record and the private school business for a second. As someone on the soft left, and given the Labour Representation Committee's 'hard' stance toward centre-leaning figures, Abbott is more likely to scoop up the 'we need an open contest' vote from among MPs than McDonnell. If that comes to pass the LRC and others should then campaign for her. This isn't because she brings "diversity" to the contest. It's because her candidacy allows an opening to shift debate and the party in a leftward direction, something that will be much harder to do if the competition consists solely of candidates who believe reconnecting with the working class means bashing immigrants and benefit claimants some more.