John, there are 4 race distances in the Grand Prix: 5 mile, 10km, 10 mile and half marathon and the times are simply added together and the minimumum total time is the winner. The mix of short and longer distances shouldn't favour the speed merchants or the long distance runners, however it does favour the 'faster' on form runners.
Typically it is the 5 mile and 10 mile races which people fail to achieve. Try and get these two in as eary as you can and if need be do any number of races to try and improve your time. I did Guys 10 on Sunday so 1 down 3 to go.
The number of people completing all 4 has been low for a few years and it may be time to review what is required. We don't handicap runners times at the moment.
We used to have the use of a notice board and displayed a list of runners with space for them to record their race times as the year progressed. There is some merit in that you know what times you are chasing, however you would probably be able to predict who the winner was going to be. As you know this year the mens result was very close.