We used to have a Bell 212 with Bristows on the North Sea with one of those fins, registration number was G-BIGB, Big B. The fin was there, I believe, because it had originally been registered in the USA, and had been an FAA requirement for IFR. It was subsequently removed, although I do recall seeing other American-registered 212's without the fin.
Vmin IMC for the 212 is 40 kts