Saving Old Seagulls

Why did they get the factory fitted Bing carb, which ran on 25-1, replaced with the Villiers?

The Bing carb was a temporary measure. Villiers were unable to supply for a while. Later motors equipped with a Villiers carb ran on 25:1 too - it's just a matter of a different needle.

Thank's again Charle's, at least I now know, there's nothing wrong with having a crosby fitted