I'm thinking somebody might find this useful.

My Ofmega quick release skewers have the lever held on with e-clips (external circlip ?).
Naturally when I bought the bike one of them was broken and replaced with some wire.
So I got some e-clips from Amazon and just about got a 4mm one to fit after quite a lot of thumb damage.

The correct size is 3/16" IMPERIAL, and will go on in 5 seconds using some pliers.