Good Morning,
From my research your tea set would have been made by William Sissons in London around the turn of the 20th century. The pieces are actually silver plated this is what the A1 means, it is the highest quality of silver plating a piece can have. EPNS means Electroplated Nickel Silver, which is composed of nickel, copper and zinc. More than likely the feet on your pieces are zinc, as many of these pieces were. As far as value your tea set silver plate is not selling for very much right now. Your silver plate pieces would run about 12-20 dollars for the cream and sugar bowl, 20-30 for the coffee pot and 25-35 for the tea pot. The demand is low for silver plate items as they are time consuming to clean and bulky to store. With the wooden handles and he decorative feet you may be able to Realize a better price as these show signs of detail used by Sissons to produce the pieces.
Thank you for your time this morning on Just Answer,
Best of luck with your silver plate,
Frank