I think that the model name of this particular frame is the "!nternational". I have one from the same year ; its rear drop-out are the sculpted Clements type that was designed for use with the very popular Cycle Benelux gears. As I recall, the Ken's winning year the team-prize was won by BSA - all riding Benelux. I reckon that history has treated Benelux gears quite badly by relegating them to almost a second - rate level. They were however far better than many of the Simplex T-d-F, with bettter chain wrap and a swifter more positive change. Probably the factor that most influenced their popularlty, or lack of it, was the fact that the Campagnolo Gran Sport was launched at about the same time and this mech with its parallelogram action was quite revoltionary, but at around £6.30 it was incredibly expensive compared with the £1.99 for thre Benelux.
It's a pity that the Ellis-Briggs that's for sale has the wrong down-tube transfers - the ones here area later model. My own frame is sparayed in deep gunmetal with dark blue head and seat panels...but carries the wrong transfers too. At the time of refurbishment, about 30 years ago E-B s had no "original" transfers left. However sets are now available froma member of the V C-C, no not Nick, for £5 per set.
Ken Russell is still about in Bradford and is still riding and he still has his Tour of Britain frame. Brian Robinson another star of those early years also road Ellis-Briggs, reputedly even in the Tour de France.. he still has his frames from that era.. and he has recently started racing again.
Norris Lockley,, from a very sunny Settle UK... what a change that makes.