Well that was a surprising turn of events. The GMB membership was polled and 60% have come out in favour of Owen Smith MP to be the next Labour Leader, leaving 40% in support of Corbyn, as there was no option to back neither or spoil your ballot.
This resulted in the GMB coming out in support of Owen Smith, despite not coming out in support of a candidate in the last Labour leadership elections.
It seems the GMB themselves are quite surprised that this announcement generated a lot of attention, at least according to their twitter feed:
Sadly this has triggered a cancellation of my membership, as I simply cannot support Owen Smith. My open e-mail below details the particulars: