I just looked it up on Amazon, Rosie, and it seems to have been 2006. They have just publishd an anniversary edition, but I'm sure it must have ben before this. Try Collins website - there's lots of information there.
One of the best dictionaries to suit your requirements is the Oxford Dictionary of English (ODE) - this is a single volume as opposed to the multi-volume Oxford English Dictionary(OED).
It contains 12,000 encyclopaedic entries and is available from Amazon for £23.49
For what it's worth, I have the 30th anniversary edition and it contains the usual geographical proper names as before, as well as writers such as Horace, Wordsworth, Mark Twain et al.