Dave. The outrigger strap 67 6046 appears on the early S/A single sided rear wheel 1954/55. The return spring wraps round the brake plate cam spigot and acts against the strap and the brake lever. Looks like the set up you have there. My parts catalogue shows 67 6046 as the strap, and curiously 42 6046 as the spring. Page 52, 1954-'57 Edition. 42 Series parts generally apply to S/A Models, tho' earlier parts carried over still use the 67 prefix. The catalogue lists the spring as 42 6046, which makes the spring part number designation correct. Whether your purchase is actually a spring that fits is a different matter....
So good luck with sorting that one out!!!
Swarfy.