The Volvo Olympians were stirling performers on the X10 (and X9).

Spectras were trialled for a little bit but their London Spec meant their top speed was a bit low.

Then before that you had Cummins L10 Olympians on the X10, but age was a factor in taking them off.

Before that the X1/X10 when United / Tees and Northern it was a mixture of Olympians (Cummins from Go and Gardener from NEB), Metrobuses (Go Only), Tigers (Both), and prob the odd Leyland National Mk2 from Go-Ahead too.