Williams won immediate acclaim with his first novel:
Long Run South was runner-up in the 1963
John Llewelyn Rhys Memorial Prize Noël Coward wrote in his diary, "I have read a thriller by my godson Alan Williams called
Long Run South and it is really very good indeed. He is an authentic writer. There is, as with all his generation, too much emphasis on sex, squalor and torture and horror, but it's graphically and imaginatively written." His second novel,
Barbouze, was even better received. Several critics said that it transcended the genre, lifting him into the top-most ranks of younger serious British novelists.
The Sunday Telegraph declared
Barbouze a compassionate thriller.
The Sunday Times praised the exuberance and poetry in the writing which the reviewer noted was then very rare in British fiction. Williams remained a favourite of the critics over the years.
Books & Bookmen called Williams "the natural successor to
Ian Fleming."
British Book News said "Alan Williams is a thriller writer who has conspicuously succeeded in the rare feat of combining a novelist's art with a journalist's training."
The New York Times critic Martin Levin said, "If you were to ask me who were the top ten writers of intrigue novels, I would list Alan Williams among the first five." His fellow writers also lauded him. Williams was a firm favourite of spy novelist
John Gardner who said
The Beria Papers and
Gentleman Traitor "were both ahead of their time" and described Williams as "one of the important figures in the change and development of the espionage novel." Gardner subsequently called
The Beria Papers one of the ten greatest spy novels ever written. Author and critic
H.R.F. Keating praised the "authentic feel" of his novels, adding "their pacy excitement derives from their author's writing skill." And according to crime author
Mike Ripley, "a good thriller can take you to an entirely foreign environment, as in the books of Alan Williams." Bestselling author
Robert Ludlum was a devotee. He especially admired
Holy of Holies, insisting that it "will glue you to your chair with suspense." ==Film adaptations==