Large 5-Tined Fork with Rd143384 & 4 Hallmarks; Ivory Handle

I think the Rd143384 (pic 6) is a design number...whose is a question, as well as whether it's the overall design or some smaller element?
The hallmarks are as follows, all in square cartouches (pic 4):
From L to R: the letters OA over SD; a Crown;
a Lion facing L with a raised front paw; the letter X.
It's ~9 5/8" long, 2" wide; its weight is ~3 1/2 oz.

Aside from the design questions (which cursory research suggests is from ~1890-1891) & whose hallmarks those are; what is the assigned purpose for this (serving?) fork: Meat? Fish? Fowl? Vegetable? Fruit? Cheese? Thanks for lookin'!

 

made in Sheffield in 1890 , and only the ferrule is sterling silver the blade is plated and possibly the handle is ivory.. purpose all above or a substitute for fingers......lol.because the Americans have a tool for every foodstuff....a sound marketing ploy.....could be out of a salad set...over to others.

 

Fish Server. Usually came paired with a Knife.

 

Assuming you have this in hand, can to take a nice close picture of the OA over SD maker's mark? I was unable to find such a mark in Sheffield. I'm thinking the letters may be different.

 

The only one with any distortion (an' it's minor, at that) is the O...which just may be a G.
I'll try to get a better shot of that, but it'll be tomorrow...Thanks.

 

Thank you. I guessed it was a fish fork, but your confirmation was pleasing!
I only learned about having a utensil for everything from members on this board, thank you all.

 

I suggest that the maker's mark is most likely CA over SD for Allen & Darwin (Charles James Darwin & Sidney Allen). This mark registered 1887 and in use until 1892 when it was superseded by their "A&D" mark.

 

These are as good as I can manage:

 

That first letter is a C alright. It is a bit of Gothic font which is why you though G or O.

 

On the Rd mark: unless there’s multiple numbers, it will refer to the whole item.

 

Very good, Obb...Thank you!

 

Most welcome.