The first direct-dialled call in the UK was in 1958; the last operator was decomissioned in 1976. Attic Term was published in 1976, so I dare say parts of Dorset were still on operator service as the book was being written, and by the time of publication it was only slightly anachronistic, not enough to worry about. Nicola does think to herself that she wishes Wade Abbas would buck up and get hitched to STD.