Hi,
Always difficult when the reference to 'lock' is asked to work out the exact part info required.
Certainly the actual lock barrel and body with the flat rotar is exactly the same as my 1970 MGB. Whilst all the other interacting parts are similar there are differences in rod lengths and the way the factory processed the assembly.
In particular the interior door handle used too on the LandRover and later Esprit on the Elan did not use the plastic frame snap finishing surrounds and the Elan just was screwed in through the back plate of the interior door handle so the assembly process was different with the interior handle itself holding the doorcard.
Not sure though of the original car that this lock part would have been used on as Wilmott Breedon were the UK's biggest lock manufacturers and like most British cars back then many components were not bespoke to the car manufacturer but common from the component supplier.
One other subtle difference can be seen on the exterior door handle casting at the front where some are slightly pointed yet the rest of the handle is exactly the same operation internally to the door lock linkages. I have seen both types fitted on our UK cars and some where one door has one of each even on Lotus cars.
The less pointed version I believe is the one correct for Lotus.
Here is a link to another useful recent thread.
lotus-chassis-f36/door-latch-lock-handle-assembly-t22604.htmlRegards
Steve