The Teleskan is interesting in a nerdy kind of way.
It appears to have been invented by Jim Tyler (BTDT) in around 1978, written up in AGW. He mounted a pistol scope to the breech block of a Webley Hawk to compensate for the weak lock-up of pinned rather than bolted breech jaws.
Around 1981-3 (I think) Webley brought out a production version, in part to compete in the “fast-fire” market with the expensive Singlepoint red dots that had originally been pushed by Sussex Armoury/Jackal.
Meanwhile, in the States, Col (retd) USMC Jeff Cooper, probably the most influential gun theorist and writer at the time, had since the mid-60s been thinking and occasionally writing about the merits of short, light centrefire carbines. His published writings started talking about the “Scout rifle” concept from 1981 or earlier, though his published thinking fully crystallised around 1983. The key feature being a low-power long eye relief scope.
A rather fascinating example (for me) of parallel evolution.
If you had a Vulcan or (better) C1 carbine with a Teleskan in 1982-3, you were cool. Maybe not as cool as the guy with an FWB Sport (that was me :-)) or an HW80, but still cool.