Just had a look at last year's results - there were 127 finishers and the last finisher was in 66 mins - so you'll be absolutely grand with around 50 mins. Plus, there will probably be more people running it this year as it's in the Oxfordshire Grand Prix championships again (last year it was only put in the Grand Prix when a different race was cancelled).
It's a funny race - you get escorted onto the airfield at the start and told that if a plane comes in to land, we'll have to stop and get out of the area! Thankfully, no planes are due to land that day so it would only be in an emergency.
