I suspect less than a dozen exist if not three or four. Done to test feasibility and costs for the American market?? The deluxe walnut stock was done in numbers and very nice they are too. Sadly doesn't make the trigger or action any better.
I would put a very high premium on this example, as Webley has a huge following. I actually put a premium on Vulcan MK1s in exceptional condition as so few survive from heavy use. Though the Vulcan Deluxe are also rare, and when found often in better condition, they still don't compete with "better" two a penny rifles like the FWB Sport or HW35E. Vulcan MK11s are about in numbers and often overpriced in shops. Omegas just reasonably priced.
I decided not to collect, but I suggest budding collectors to grab any that are in exceptional condition. Condition for 80s rifles and scopes is everything if for keeping.