Thanks Jim for all this interesting information. I just got this great helm from a long time collector, who purchased it from a specialized dealer in 1993. It was previously sold at Sotheby's or Christie's auction a decade before, at 8,000 £ (from memory, he did not remember exactly which auction and is currently looking for the corresponding catalog page among his tons of papers; I will let you know ASAP).
To Jim: The link to the photo has been provided in my previous post