It might not be the same fitting on yours but image below is link to the retaining clip used on the Lucas PRS 3 ignition/light switch of that era.

[Linked Image]

If your switch body has similar grooves for retaining clip the above should solve your problem. Failing that complete generic PRS 3 switches as used on many cars and Land Rovers in the 50's and 60's are occasionally available on eBay. Although there are a few style variants the wiring remains much the same between them accepting that later ones have lucar spade connectors.

Last edited by RichardV6; 11/10/21 08:17 AM.
Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone