His father, George Watson, was a printer and stationer, and his mother, née Emily Manning, one of a large family of fairground travellers.

One of his later academic works, Reading Series Fiction: from Arthur Ransome to Gene Kemp,[11] allowed him to focus on the genre of children's books he is most interested in.

Subsequently, he wrote a series of war stories for eight to thirteen-year-old children, beginning with Paradise Barn,[12] which was shortlisted for the Branford-Boase Award.

[19] In June 2020 Watson published his first novel for adults "The Cuckoo Season" which is set in East Anglia and London in 1952,[20] and in 2022 the book he edited about Lucy Boston was launched.

"[22] Almost from its inception, Watson has been a trustee of an organization committed to establishing in the UK a national archive of manuscripts, artwork and books relating to children's literature.

He chaired this organization during the main fundraising and building period, which led in 2005 to the opening of Seven Stories, the National Centre for Children's Books.