Not sure about 2366 but by the sound of it it is a Lisburn bus and they quite often get swapped with Downpatrick buses for short periods---no idea why. The destination blinds don't have anything in common except Belfast so it is awkward. Even though Downpatrick buses work to Lisburn from Saintfield 2 or 3 times a day now hardly any of them have Lisburn on their blinds.As far as I'm aware there have never been any REs allocated long-term to Downpatrick in the 11 years I've been getting buses. Although 2 of the ROI batch were allocated to Downpatrick when new around 1978, I don't know how long they stayed for.
178 was in DP for a good long time---several months at least. I think it was some time in 1999 and in fact it might have been in DP between V and CL. It didn't even have a destination blind most of the time it was in Downpatrick and was mostly used on school services.
4 Second-hand Renowns 2774-7 (BCZ 2774-7) came from Citybus to work on the service 18A Carryduff to Belfast via Botanic Avenue QBC which is operated from Saintfield sub-depot of Downpatrick. 3 of the buses live there and a 4th spare one is kept in Downpatrick all the time. It gets used on all the ordinary rural services and is seeing a big change from work in Belfast. As well as the 18A the buses in Saintfield also do some duties on the 5B Ballynahinch to Comber and Comber to Saintfield.