It's the make of vehicle. http://www.johndennisfire.co.uk/

Ah, if you look carefully you will see many of them don't any more - they say "Scania", which are the more modern engines. The Dennis ones are old-school, and for the most part have been passed on to fire services in Russia and the rest of Eastern Europe. (And now a whole generation of Russians are wondering why fire engines are all called Dennis) John Dennis Coachbuilders still make a good deal of British Fire Service vehicles though. Incidently, I have met John Dennis.

Dear Lady Fuschia , scania do not make fire engines just lorry chassis that are adapted by coachbuilders and made into what resembles a fire engine but a fire engine they will never be , dennis are not old fashioned as the sabre is in fact a newer design of cab than the scania and dennis are designed as fire appliances not tipper lorries ,if you want more information why dont you ask john dennis who no doubt makes a good living converting lorry chassis into fire appliances ,dennis are better handling ,easier to get in and out of , some cabs depending on specification are roomier , faster , and because of these are safer , they are made from stainless steel and dont rust they last a lot longer , you wont find scanias or the like secondhand in russia and are the preferred type of many many fire fighters who have to use them on a daily basis ,they are not as common as they once were due to scania and the like selling chassis cheaply to use them as a halo product (some offers are unbelievable)so there you are a firefighters viewpoint ,oh yes scanias are a bit quieter inside and that is their only plus point as far as i am concerned