Hi Stuck
Could this be your Arthur in 1901? I know it's his brother who is the Edmond , but after lots of different searches he is the only possible match I found. The Walts looks like Watts to me on the original image.

Jan
Arthur E Walts, 7,Son, born Paddington, London, England
Laburnum Cottage, Gordon Ave
Harrow Weald, Middlesex
RG13/1210 Folio 80
Arthur E Walts 7 Paddington, London, England Son Harrow Weald Middlesex
Edmund A Walts 8 Paddington, London, England Son Harrow Weald Middlesex
Edward R Walts 32 Marylebone, London, England Head Harrow Weald Middlesex Plumber
Elizabeth S Walts 29 Mentmore, Buckinghamshire, England Wife Harrow Weald Middlesex
Ellen M Walts 3 Harrow Weald, Middlesex, England Daughter Harrow Weald Middlesex