Why did the count start this morning?

Ben Brogan has noted it just before I was going to, but I have just come off the phone to someone at one of the London counts and it is looking very likely that we're going to have wait quite some time more than the original prediction of an 8pm result.

The question this raises for me is that, given there is electronic voting, why on earth did the count not start at 11pm last night? So far the count has been going for about nine hours. That is one hour less than the ten hours that were wasted doing nothing between 10pm last night and 8am this morning.