Hello Steve, welcome and thank you for some nice interesting marks to start off with. I think you will get quite a few opinions as to the manufacturer of your Mum's spoon.There are no letters to help but the pictorial marks may be traceable. The association of the middle 2 marks do suggest one maker to me. That is Joseph Rodgers of Sheffield a very long established company who are referenced as "Old Sheffield Platers" in 1822 and subsequently as electroplaters in the 1860's. I think your spoon may well be a fairly early spoon and below is a much later mark.
I think the thing to compare is the the top 2 marks as being a later version of your spoons middle marks. There is possibly one other bit of evidence from the "Old Plate" period in that it is recorded that a "battleaxe" was a trade motive for the early concern. "Rodgers" were later "and Sons" and "Ltd".
The last mark I see as a cats face and it was far from rare for early electroplaters to use marks that could be mistaken for true silvermarks. A cats face being found on silver made in London. As a note if you are not familiar with Old Sheffield Plate it was the method of fusing silver on to a base metal before electroplating was discovered.
Well I have given my view but prepare for a few others from some more experienced "forumers".