Hi,
took the T120R out for a blast. Got back home and reached down to the side panel to switch it off... no key. Not only was there no key but there was no lock barrel either.
A bit pissed off 'cos it was a brand new Lucas (Wassel ?) ignition switch that had only been fitted less than 1,000 miles ago. Fortunately, it looks like the switch is OK and I only need to buy a new barrel and keys. Might have to think about an alternative arrangement.
My key switch failed last week after a very long time.
Ordered a pattern one
Its not a Lucas for certain.
will be interesting to see the quality.
Risking telling you things you know already:-
. Despite the different five-figure part numbers, it's the same switch on your bikes as the T160 and '79-on twins switch. These often 'fail' due to internal corrosion, due to their upright position and no drain for any water that gets in.

The base with the terminals can be prised carefully from the case (usual caveat about flying springs) to clean and grease the terminals. On T160 and '79-on switches, I drill a small hole in the lowest point of the base, so any water that gets in can get out too.
. The T160 and '79-on twins switch securing ring allows use of either of their arrangements to better-seal the lock. Electric-start Commandos also used the same switch; because the console was open at the bottom, they have a cover for the terminals end of the switch too. Pm if you want the Notrun part number.
. The only thing that keeps the lock in the switch is that spring-loaded pin; worth checking that it's properly-engaged in the lock?
. Ime, things to note/check on pattern switches:-
.. The terminals aren't numbered on some. :bluduh If so, before pulling the wires off the old switch, maybe mark the pattern switch's terminals then check the functions with a multimeter?
.. Some have all four terminals as double tabs. However, others have one terminal as a single tab. Patterns of this type position the terminals closer to the metal casing than originals, the single terminal can be twisted on its rivet by attached wiring and touch the metal case ... :bluduh
. From the memory of losing the keys from the ignition lock of my 250 Honda (under the tank :bluduh) many years ago, the key for the T150 and T100 is on one of those stretchy coiled key-cords - 99p or £1 from the corresponding shop.
Hth.
Regards,