Hello, I think there is a good chance your dating of the spoon is not correct. In the early 18th century, English silver was marked for a the higher grade of silver called Britannia Standard, and not marked with a standing lion. The spoon is later with gothic styled date letters, in the date range 1756-1776. I think the date letter could the gothic style "T" for 1774, so William Fern could be a candidate as the silversmith. Obviously that date letter is not crystal clear so possibly there will be other views.
I agree 100% with Fishless's assessment of the maker and date - William Fearn, 1774. Note that the picture of the hallmark has the date letter and lion passant upside down. Here is my exemplar of a 1774 hallmark for comparison: