Rob
Thanks for moderating this thread
Gilles thanks for your input on the weapons side.
The Kings Troop guns go out on a regular basis with a reg force unit but admittedly in ceremonial role.
So to clarify, in use for "work" we have the DUKWs in the UK
Link here to some pictures
http://www.18coyrasc.btck.co.uk/2010REUNION
and in the "ceremonial" category the Kings Troop 13 pounders
http://en.wikipedia.org/wiki/Ordnance_QF_13_pounder which according to this link were actually made in or started production in 1904. This makes them over a century old according to my math.
R