The garter is not hereditary. You need to stick with an earl who was a knight of the garter at the date the forks were made, bought and engraved. The garter is not that common in engravings on silver because there is a limited number of knights at any one time and they don't all necessarily include ...
An internet search should bring up a list of Knights of the Garter with their dates. The Earl of Winchelsea was a knight at the right time. His crest, a pegasus, seems to me as close to the one on your forks as anything, but you might want to check this out for yourself.
The letters on the key simply spell out Leningrad. I don't know the maker's mark, but the 9 could be a date code and the L Yu might stand for Leningrad Jewellers
I am not so sure we can come to this conclusion. It seems to me quite probable that the cup was smuggled into England in the 1860s with the aim of passing it off as an antique - many "experts" were less knowledgeable, or more gullible, back then and this sort of thing did go on.
Looks like 1776 to me based on the outlines of the punches. My eyesight offers no help with the maker's first initial, but if it is a W.C mark I confess that I give up when it comes to identifying which of the many WCs around this date. Maybe somebody else is able to be more confident.
I make that London 1893, maker probably Edward Dimes - the outline of the ED mark punch is not an exact match but I am assuming that may be the result of wear.
Yes, it is English. From left to right the marks are: date letter (Gothic L for 1766), Leopard's Head crowned for London, lion passant for sterling standard, and IM for an unidentified maker.
It is generally safe to assume that 18th century apostle or seal top spoons started life as Hanoverian (or Old English) spoons and were re-worked in the 19th or early 20th century when their finials were added to exploit a growing collectors' market. I hesitate to condemn your spoon outright on the ...
Just checked my catalogue and see that I have described a pair like this as salt shovels. They are also 10.5 cm long and are by Geo Smith, 1798. I see the bowl shape as transitional between the earlier proper shovel shape and the more usual bowl but perhaps that is to read too much into a design qui...
I think a surviving set of spoons with an ownership provenance that takes them back 200 years or so is of real interest even if the cash value does not match that of 300 year old spoons. As regards how to date them, the most obvious feature is the "coffin end" to the stem, a typical Americ...
Sorry - I should have re-read your initial post. I imagine I didn't chip in with this thought earlier precisely because you had it first, but I think it is a more probable explanation than trying to construct a message across two languages.