(19 Mar 2014, 6:44 pm)tyresmoke wrote Might well have been covering mileage or something as a spare bus

I think judging by previous posts on the Latest thread, 22021 was brought in to cover for 36965 which had developed a fault near the terminus of the route.

As soon as 36965 was active again, it replaced 22021.

Why a section of the route was served by neither vehicle, I do not know.