(12 Dec 2020, 2:31 pm)IRHardy wrote In 2020 Oxford gained 2 contracts (Bicester Village shuttles & Milton Park shuttles) which dictated the use of euro 6 vehicles, Oxford did not have any spare euro 6 double deckers and there was not enough time before the contracts started for a new order to have been placed and the new vehicles being delivered.
Probably because the Oxford contracts were more lucrative to the Go-Ahead Group as a whole than Go North East’s plans for the 9 StreetDecks, the Group brokered the exchange, as Oxford had spare coaches that it had no longer any use for (following the withdrawal of the X90 London to Oxford), so Oxford passed the spare coaches to Go North East & Oxford took the new 9 StreetDecks for the new contracts.

Arriva Midlands have done the same, there was a batch of E400MMCs for the Leicester - Oadby services, but Arriva won a University of Nottingham contract which required Euro 6 double deckers, so the buses got moved from Leicester to Derby (who operate the UoN routes). The Leicester - Oadby services regained the older buses that they had lost only a few months earlier.