Just want to say thanks for the ideas and suggestions and to say I think I now have it all sorted.
The seat is interlocked to the ignition, as is the reverse when the cutter is down and the start unless the brake is on and the cutter fully raised. Which makes it a bit of a pain to reverse a yard, having to raise cutter to select reverse.
The one thing which makes it really awkward is the brake cum clutch pedal on the left. It is a very long reach forward and just about reachable with the left toes and I cannot see any obvious means to adjust its position. 6' 6" friend also even finds it a bit of a reach.
Other than that everything is fine.