Hi,
It's not the answer to your question, but if you're looking to replace the horn push assembly - the casing/contacts/spring then I replaced the one on my Elan '68 S3 with a Triumph one. I'd guess that the early S1 Europa wheels were the same ? The later steering wheels on the Elans and on my '72 TC are different with a larger horn boss and I've yet to find an alternative for those.
As for the change of badge colour, that's almost heading to the "was it because of Jim Clark or not ?" question. There's plenty of evidence that Lotus had black badges prior to Clark's death, Arnold's company car was in road tests showing the black bonnet badge. My Elan has a black badge horn push but green/yellow bonnet badge so the horn push pre-dates the bonnet badge. Or maybe that's just what Lotus had on the shelf at the time
