Norman Ashby was a pseudonym employed by Mervyn Haisman and Henry Lincoln for the Doctor Who story The Dominators, as they felt unfairly treated by the production team and requested their names be removed from the credits. The pseudonym was created from the forenames of Haisman and Lincoln's respective fathers-in-law.
It would appear that Haisman and Lincoln's decision to use a pseudonym came at a late stage, as the scripts that exist today bear their own names.
The short story Do You Love Anyone Enough? in Short Trips and Side Steps also used the pseudonym Norman Ashby.