Hello Windag, my experience is fairy lacking in early 18th century silver, but I managed to enlarge one of your images without gross pixilation. I think a similar mark is seen on the website silvermakersmarks.co.uk. Turned 180 degrees, I thought one mark on your spoon could be "JO" and there is a similar mark, JO under a crown like serration, with an attribution (probable) to Lawrence Jones of London. That mark has been seen with dates 1706..1713. You have a date of 1720 on your spoon. Maybe you could post a large image of at least the crispest mark again for others to view and give opinions. My image is below.
Fishless