The Wallace Arnold one isn't a Guy Wulfrunian, it's a Volvo Ailsa. Both are quite similar, in that they have a front enterance alongside the driver, but also have a front engine. The main difference was that the Ailsa was a sucess, the Wulfrunian wasn't. Unlike the Ailsa, which other than it's unusual engine position, was fairly conventional for its time, the Wulfrunian had loads of advanced features such as air suspension, all round disk brakes, all of which cause problems, aswell as having a large engine unsuited to the front engine, front enterance layout, unlike the Ailsa which had a much more compact engine. They also suffered more conventional problems relating to the cooling system, and chassis. One other big difference was that the Wulfrunian was built in the late 50s, at a time when rear engined double deckers were new, and front engined halfcabs were still being built in large numbers, and was designed to grab the market who were still unsure about the new rear engined buses. The Ailsa on the other hand was built in the early 70s, with production running into the 80s, at a time when second generation rear engined double deckers were in prouction, and many of the revolutionary features of the Wulfrunian were standard, and many were in service until a few years ago, and quite a number still are.