Only a guess, but I would imagine that it's perhaps 'semi preserved', i.e. they use it on normal duties from time to time.
Close enough. Both Western Greyhound VRs are in WG's Heritage Fleet:
Western Greyhound Heritage Fleet (6)
RM1062 62 CLT AEC Routemaster roller blinds RM1062 Park Royal H38/26R 1/1/62
RMA11 NMY 648E AEC Routemaster roller blinds R2RH22854 Park Royal B54340 H33/24F 03/03/1967
RML2737 SMK 737F AEC Routemaster roller blinds RML2737 Park Royal H40/32R 16/11/1967
RF141 MLL 528 MLL 589 (RF202) AEC Regal IV roller blinds 9821LT1050 Metro-Cammell B39F 25/03/1952
258 LFJ 858W analogue Bristol VRT/SL3/6LXB roller blinds VRT/SL3/2674 Eastern Coachworks 24477 H43/31F 01/12/1980
259 JWV 259W Bristol VRT/SL3/6LXB roller blinds VRT/SL3/2757 Eastern Coachworks 24661 H43/31F 01/02/1981
http://www.flickr.com/photos/29197902@N06/4535231927/
And usually comes out to play on the route 501 - Penzance - Porthcurno - Lands End Sennen Cove - Penzance. In fact, ex Western National LFJ 858W is branded for this service. The other Bristol VR in WG's Heritage Fleet is ex Southdown JWV 259W, which is / was a convertible open topper.
In fact, quite a few companies will still use heritage vehicles from time to time & for various events. My local, Stagecoach in Hampshire has recently saved one of the original Leyland Olympians - F601 MSL and refurbished / repainted it back into original condition. This has been joined by repainted / refurbished Bristol VR JOU 160P, and at last weekends Goodwood Revival - Stagecoaches very own Bristol FLF Lodekka JAH 553D.
That should do for now, rather tired and have to be up early in this morning so i'll try and do a better post this evening, but theres an answer for now. Oh and if you want a Western National fleet list:
http://www.westerngreyhound.com/enthusiasts.php
Another place where you can still find heritage vehicles in service are Dartmouth for the Paignton & Dartmouth Railways bus services usually in the summer a few ex Southdown VRs, and also in summer a open top Leyland Atlantian now owned and operated by Xela Bus in Portsmouth.