The larger chamfer goes towards the crankshaft face as the corner is a radius and without the chamfer the thrust washer will not sit against the crank face.
That's what I initially thought but looking at the two examples that I found and shown in my first post a chamfer is facing away.
The shim that was originally on my engine only had one side chamfered, not both, that's what threw me as it made me think they were all like that - only one side.
All sorted now, got my new shim in, wet and dried the c clip with a bit of WD40 to give 4-5 thou.
Cheers,
Ian