I seem to remember seeing 9:15 as the start time but I can't see this on the website now. I did find the following hidden away in the FAQ though which may be some help:
"What time do I need to get to Victoria Park by?
It is advised that you aim to arrive at Victoria Park at 8:00am on the day. This will give you time to deposit your bags, kit, and valuables. To prepare, warm up and stretch. You’ve been preparing for this event for months so don’t rush the last part, don’t place extra pressure on yourself by being late for the start. Runners should be there by 9:00am in the starting pens."