Ok see here web page
and you will see my problem. I think it is caused by me leaning too far forward but I'm willing and keen to rectify this so any tips and advise much appreciated
you're rotating forward on your hands, very common problem. if you remember to lift them to just above the mane intermittently, you'll have to keep your weight down in your heels, and use your balance.
e.g. same applies over fences - push hands up neck towards ears but not touching mane, and it keeps your weight down, stops you rotating forward around your knees onto your hands.
hope that makes sense!