3.5 feet roughly. Doesn't matter too much how high the take off is. You get plenty of air time and land in the right place. Harry Hemmings, who was riding with you at rogate was more scared of this jump than he was the big doubles at rogate Will.
those must be some tiny doubles. Trust me that lip is 3 feet max. im 6 ft 3 and my waist is almost exactly 3 ft. the gap size on that is like 10 ft so its not a big jump. you should make the lip another 3 ft taller and move the lander out to around 12-15 feet
But this is a long time ago. This was big to me then.