Sheffield plate silver candlesticks

Hello experts

I have recently purchased a pair of stunning matching candlesticks from a local good quality car boot sale. They seem to have an art nouveau look to their outer design but appear to be of an earlier style. The candlesticks have 4 old scroll letters and some other mark in between which is indistinguishable as it seems to have been polished away. The two first and two last letters could possibly be EP and NS but again, difficult to make out. The underside looks ancient with a dark brown weathered material with some old black pitch inside base. The candlesticks have what appears to be a seam running down each side of each stick down to just below the top of the base. I am unsure as to whether they are of thin silver or silver plate on top of copper. Their condition is very good with only one of the sticks having the top part being a little squint and both sticks needing a proper clean up.

Could anyone give me a rough idea of the period they are from and any other relevant information, value, material etc.

Many thanks

Alex Tickell