I’d never heard of ADP either, but could the difference be due to the weekly payment being slightly different from PIP? It’s often confusing on this forum when people quote the WPMS (war pensioner mobility supplement) APs, as they are very different to the APs for PIP recipients (which, I assume, is the vast majority). However, as the benefit rates are different, if you add 3 years worth of the different benefit payment levels to the different APs, they both work out the same over 3 years. Maybe that’s the same reason why the APs for ADP recipients are different?