ROBERT Louis Stevenson would have been a millionaire had his books such as Kidnapped, The Strange Case of Dr Jekyll and Mr Hyde, and The Bodysnatcher been published today.

Organisers of the annual RLS Day on his birthday, November 13, have assessed he would be in the same league as Rebus author Ian Rankin, fellow novelist Val McDermid and noir author Christopher Brookmyre had he still been alive.

As a rough indication of how much Stevenson could have made, Kidnapped alone would have earned more than £220,000 a year in royalties.

His words are available for free at Project Gutenberg, which the trust used as an indication of the popularity of Jekyll and Hyde, Kidnapped and The Bodysnatcher.

It found between them, 82.34 per cent of the downloads were from Jekyll and Hyde, 16.72 per cent were for Kidnapped and just 0.94 per cent for The Body-Snatcher.

Jekyll and Hyde has been the subject of more than 200 film and TV adaptiations, which would have earned Stevenson at least £200,000 more for the book. This would have left him receiving an estimated £1.305m.

Ali Bowden, director of the Edinburgh Unesco City of Literature Trust said: “We don’t think of Stevenson as a crime writer, but his links to that genre run so deep that RLS Day this year lets us look at his lesser-known writing.”