It seems apparent that Idris is on the money that this variation is not among the rarest of vintage Lesney toys. I remember a few years back when the flurry of discussion surfaced on the MCCH with regard to the discovery of the 25b Volkswagen with the misspelled bases. We soon learned that, while somewhat difficult to find, they were out there for those that keep looking long enough.
After finding this thread about this early variation of the 41a I had been watching ebay for less than two weeks when this one surfaced out of Australia. I think some others (probably some of you guys) found this one on ebay too based on the level of bid activity. Anyway, it's in Ohio as of Monday.
This one's got two dandy decals but some paint bingos.
I don't see any unique projections or features on the base: