Hi John,
Welcome to the Forum.
Your spoon is silverplated.
I don't recogize that mark and can only guess at it, but it a likely that your spoon was made by Henry Wilkinson & Sons of Sheffield. They were a known user of that cross keys mark that appears to the right of your mark image.
See:
http://www.925-1000.com/silverplate_W2.htmlThe 'M R & S' marks may well be that of the customer of whom Wilkinsons made the spoon for. It was not unusual for a retailer, if they placed a large enough order with the supplier, to have their own mark struck upon the items.
In this case, the 'M R & S' mark may well be that of Manoah Rhodes & Sons of Bradford, and the 'K' a possible indictor of their Kirkgate address.
See:
viewtopic.php?f=38&t=19000The '1A' mark is a typical quality mark used in the silverplating industry.
The above is speculation on my part, but everything does fit nicely together.
Trev.