The Arriva output from Peterlee wasn't all super-powered Deltas, Scanias and Olympians. They had some Metrobuses and ex-london Leyland Olympians which could have rolled back down Crimdon Dene given half a chance.
I certainly agree with this as the slowest / most clapped out bus I have ever been on in service was Peterlee's 7263 (TPD116X) back in Dec 2004.