A friend of mine has just told me about a book supplier called TheBookDepository.co.uk.
The price of a book which I purchased from another source was £2 more expensive.
The difference is accounted for by the postage and packing charge. Their website states that there is no charge for delivery.
Should have added:
Check lines 5 and 6 in Description (click "Learn more") to see whether hardback or paperback, and condition - I usually decline anything less than "very good".