Just found this lovely mystery lightweight machine, probably late 60s.
No badges/decals to indicate make, but has good mid range components and in good working order.
Rode it for 10 miles or so yesterday to bring it home and it works perfectly.
Looks original and little used, and spec as I know it now is:
GB stem and Coureur calipers.
5 speed with Atom flip flop hub.
Bayliss Wiley BB with oiler nipple.
Steel wheels, Huret derailer/changer.
Blumels lightweight guards and reflector.
Obviously from a small maker, probably Coventry made.
The triple triangle fame is quite distinctive.
(Did GT copy this??)
Cleaned up/lubricated a little from how it appears here and it rides very smoothly.