Rusty,

Thanks very much - and I think I've sorted out my confusion. The
books are written from a US perspective and they are talking about the
US 4 wire system - 2 hot wires, a neutral at 0v and ground. So it
makes sense to ground the neutral. When read from a UK perspective
with only a 3 wire system, then it makes no sense to ground the
neutral, which is a hot wire. I've since found an excellent web
search searching through this group which has some really usefull
wiring schematics - which also confirms that it is a real snakes'
wedding with 400v, 240v, 24v and 12v systems!!!

Colin