Im not sure if it is still their ?
Bus their used to be an old Mk1 coach near platform 1 at Huddersfield station , not sure what it was used for ?
There's a pressure ventilated mark 2 carriage to be found by the lineside at Halifax that has been there for some time, and was recently refurbished and repainted by Northern Rail for the National Children's Museum:
http://www.rail-news.com/2010/02/11/northern-rails-eureka-moment-2/
Up in Northern England, we're quite fond of integrating old railway carriages into the structure of pubs and restaurants. Probably the most well known of these is "The Sidings" restaurant and B&B at Shipton by Beningbrough (
http://www.thesidingshotel.co.uk/index.php/home.html), due to it's location adjacent to the "racing stretch" of the ECML between York and Northallerton, which incorporates five mark 1 carriages into it's design.
There is also however the Pullman Lodge Hotel on the seafront at Seaburn in Sunderland, which has three 12-wheel wooden panelled Pullman cars "bolted on" to the front of the main superstructure. For many years these were painted sympathetically in the traditional Pullman umber and cream colour scheme, however in more recent times they have been repainted all black, as if in an attempt to disguise their very existance.

Round the back there is also one more recent mark 1 vehicle that has had part of the bodyside cut away to make it a more integral part of the main building.
Personally, I prefer "The Rattler" in South Shields (Named in memory of the "Marsden Rattler" passenger service that used to ferry colliery workers down to Whitburn Colliery from South Shields), which has incorporated three BR mark 1 carriages (Including a suburban compartment vehicle that has been converted to house the kitchens) into it's structure, with the "inside" bodysides cut away entirely to integrate them seamlessly into the main building and increase the total floor space. The all-over maroon livery that they currently wear is looking quite drab at the moment, but the interior of the place is very pleasant, and there was a time when these were surely the only mark 1 carriages to carry a "giraffe print" livery under a previous management! The main building is also topped by the clock tower from the old Manors North station:
http://www.disused-stations.org.uk/m/manors_north/index65.shtml