The Bell Colt All Transistor was manufactured by Bell Radio-Television Corporation Ltd in about 1961.
This reasonably scarce transistor radio is the only portable Bell Colt style set. It used a 9V battery mounted directly (albeit upside down) on the chassis, while every other known model was designed for 230V AC. The old-style large brick 9V battery was held onto the connector using elastic straps that ran through holes in the chassis.
Some had a push-to-light arrangement on the tuning shaft for the dial lamp to help conserve battery life although the photographed model has no dial light at all so this was possibly either a later modification, an early but unreliable mod or perhaps there were two versions.
Interestingly the Columbus Radio Centre advert suggests it was made especially for them, although this seems unlikely since Columbus had their own battery portable sets.
An interesting ommission in the cabinets - blue is not advertised as an available colour. Also note the push-on plastic knobs appear to have metal inserts in the advert.
Valves (7 Transistor):
Chassis Notes (most schematics can be clicked to download a full size version): The chassis appears to be a standard Bell Colt folded aluminium one with the centre cut out and replaced with paxilon or a similar type of insulating panel, which then has rivets or studs mounted in locations where components need to be connected. No known schematic, one could potentially be reverse-engineered from this model.