Sorry guys.. never post to the CR List before that first cup of coffee takes hold...
The Lenton Sports range DID have 26 x 1 1/4" rims throughout its production (1948-1958); the Marque II and Marque III Lentons (Lenton Grand Prix) had 27" HPs.
The other machines in the Raleigh-Rudge-Humber range with 26 x 1 1/4" was the Trent/Ulster/Beeston Sports, the 2030 steel version of the Lentons.
Peter Kohler
Washington DC USA