I'm going to add again, whoever owned your Lenton loved it and rode it.
The upgrades he made to the derailleurs and rims were conscious choices to keep riding it while others were buying newer bikes.
The upgrade to alloy rims improved the response of the bike, its climbing ability, and especially the braking.
His changes might have ruined the bike for some collectors, but you got a better bike for them.
The catalog-perfect thing created the market for parting out historic bikes. When I tackled my Lenton bare frame, I knew it would cost as much to hunt down the original Williams crank, wheels, derailleurs, etc. in the buy-back market, as it would to design and build my custom. I ended up with a better bike for it.
@LouB a project for you might be to take the rims you just removed from your Charrel, and have them rebuilt on your Lenton hubs (you've already changed gearing and RD).
Those wide rims would go great with the reach and travel of the GB brakes.
Wheelbuilding charges at Howard's shop are much less than most, and the work quality is higher than most.
Also, you can't simply swap out wheels, because the axles on the Charrel wheelset are too big to fit the Lenton dropouts.