Welcome to the Forum Scott.
In my opinion what we have here is a cast spoon assayed at London in the 1770's.
Between about 1770 and 1780 Goldsmiths Hall performed many experiments on hallmark positioning. An article was published in 'The Finial' (Vol.14/06) by Anthony Dove, in it he illustrates a four tined fork by Thomas Heming c.1770 struck with only a Lion Passant along side the maker's mark placed at the base of the tines at the rear, and another example of similar marking on a George Smith fork c. 1775. These experiments were probably to prevent damage to the decoration that was becoming more and more popular on flatware and space options for marking on a suitable flat surface becoming increasing smaller.
Here's an example of a different marking position that was tried out at this time:
Dublin also experimented:
As can be seen from the Dublin example, there was no space on the stem for the current system of bottom marking.
That leaves us with the mysterious 'TJ'. He is likely to be one of the entrants in the missing Largeworker's register (1758-1773). There was nothing to stop Largeworkers making small objects, or vice versa. The silversmith, 'TJ', however, will, at the moment, remain a mystery.