In 1985 as reported in Chessics #24 p.92 he made a computer check on the de Hijo (1882) enumeration of 16-move knight paths in direct and oblique quaternary symmetry, which I recently (Sept 2016) published in diagram form: http://www.mayhematics.com/t/qp.htm
He also did significant work on Fiveleaper tours including 52 magic tours, which have a page to themselves in the Knight's Tour Notes: http://www.mayhematics.com/t/pf.htm
Possibly his most notable work was his enumeration of all the "regular" magic knight tours on the chessboard (that is those formed of Square, Diamond and Beverley quartes) which was reported in the Problemist January 1988 (p.379) with diagrams of five new magic tours, the first discovered since the work of H. J. R.Murray published in Fairy Chess Review in 1939.
Although we corresponded over several decades we never met in person. I had the impression that he was younger than me, mainly in view of his expertise with computers, but perhaps I was mistaken. I will update this page as further details come to light.
UPDATE 26 April 2017:
I should also have mentioned his discovery in 2003 of the unique 10 by 10 semimagic knight tour with quaternary symmetry that I published in Games and Puzzles Journal (online):
From the new information below it seems that TWM was a good deal older than I thought, and also a rather adventurous individual!
I have heard from Mrs Dorothy E. Marlow as follows:
He was Thomas William Marlow, born 24 January 1927. Apart from his National Service, which he spent mainly in Burma, his working life was with the LCC/GLC, taking early retirement when the GLC was abolished. He then became an advisor for the Citizens Advice Bureau, which for more than 20 years he found stimulating and rewarding.
His personal hobbies/interests were anything and everything concerning Mathematics. I always said that he was a human computer! He also liked travelling - as independently as possible as he disliked organised groups, although sometimes they were necessary. Most of our holidays were of the walking / trekking / backpacking type in such places as the Himalayas, the Andes, New Zealand, etc. In the UK it was anywhere among the mountains - Snowdonia, the Lake District and the Munros in Scotland. As the years started to take their toll, it became long-distance footpaths & coastal paths. I have some wonderful memories.
Another hobby, which I nearly forgot to mention, was gliding. He had been a glider pilot for about 60 years and kept his own glider at the London Gliding Club at Dunstable."