336 is not a brand new last. It's at least 10 years old but has only been used for the Moltons which DC has been wearing for a while. I remember reading about it on the C&J website but can't find that info now.
I'm a 7.5UK in most brands, C&J, church, RMW etc. I own a Chiltern in 7.5UK and have tried on numerous C&Js and always found this size works best. But recently I tried a pair of green Chilterns and Moltons and I think I can get away with a 7. So either my feet have shrunk or current C&J shoes wear a bit bigger than they used to.
Found it
LAST NO. 336
Launched in April 1999, the 336 last is a well-balanced main collection last, with standard ‘E’ fitting measurements and good tread width. The blunt square toe will result in the wearer’s toes sitting relatively close to the front of the shoe, but the shape gives a commanding look and feel working well with hearty Derby shoes and boots with storm welts.