Arkle was the best jumper ever.
He was the only horse, flat or jumper, for which the rules had to be changed.
If he was entered in a handicap (and he won plenty) there was an "A" handicap and a "B" handicap. If he ran, the A handicap was used, if he did not the B handicap was used.
In the A handicap there were lots of horses of varying abilities stuck on the bottom weight.
In the B handicap they were weighted to their true abilities.
Kauto Star was a super horse, but Arkle could have gave him over a stone advantage and a sound beating.