Just follow the inevitable 17 year old who sprints off at the start to either a) run a sub 16 time or b) blow up after 1km and finish in about 25 minutes...
I'll give it a go next time. Be nice to go sub 20. I guess I think of the front being for the proper/fast/whatever runners and I still don't really think of myself as a proper/fast/whatever runner.
@Arducius go off the front its only 20 minutes effort. smash it