The EPNS stands for ElectroPlated Nickel Silver, i.e., just plate, not sterling. The other two marks are fairly generic, and were used by a number of manufacturers. The crown indicates that the dish dates from before 1896 - after that date, it was illegal in the U.K. to use the crown symbol on anything other than sterling that was assayed in Sheffield.
The cropped part of your photo might tell us something about the maker. But in any case, the piece will almost certainly be of decorative value only - it contains virtually no precious metal.
Thank you SO MUCH!I will try to get a better picture
What I’m looking for is some sort of maker’s mark - a name, some initials, etc. But there might not be one.
As I feared, there’s nothing there that would identify the maker. The “crown within a shield” might be more specific, but I can find no reference to it.
In a way, it doesn’t really matter. Electroplated pieces were made in their millions, and if the plate is badly worn, as it appears to be on this dish, it’s worth nothing, so no one much cares who made it. 
The fleurs de lys was used inter alia by JJ Waterhouse and Thomas Small. Small was a Birmingham maker. Waterhouse was a Sheffield shop but used a stylized mark rather different to the one you have on display.
The crown can imply a Victorian date on UK items as the Sheffield Assay Office acquired exclusive use of the crown some time towards the end of the 19th century. However this prohibition on the use of a crown does not hold outside Britain. (Ref. Phil Osborn, July 10, 2010 this site)
You will note you have an indent into the fleur de lys mark which would have been the end of the maker’s nomenclature. If you feel like a detective hunt through mark ends.
This item is one of a pair of bottle sliders or as the Americans call them coasters.
Depending on where you live there will be someone around who has a catalytic converter which will cover the copper with a thin layer of .999 silver. THe cost is usually fairly minimal.
There are kits you can buy to do it yourself using a different chemical process, but they are rather limited in capability.
Call up your local friendly silversmith and see what she or he can do for you.
Here’s two pairs of electroplate sliders selling for $225 plus buyer commission in the US in 2017:
and another pair selling in your country, given you hang out in the UK and aren’t Welsh* for 30 quid:
As Jeff says barely worth the effort by the time the auctioneer takes his cut, but if it has sentimental as well as intrinsic value go for it.
Christopher
Guildhall Antiques,
Toronto
- I get in trouble from my Welsh friend for suggesting they are even vaguely English. Although they did rule England when the Tudors were in power and their successors are still on the throne mixed in with some very dubious Scots. (The Stuart family actually originated in Lancashire and were called up to Scotland to act as stewarts and sort of took over) and more recently a lot of Germans who got the job because they weren’t Catholic.