Need help with a pendant's hallmarks

I have a 1 oz. bar pendant I was reciently given by my Nanna and need some help deciphering the Marks.
So far I have worked out the Yorkshire rose reprisenting the Sheffield Assay Office post-1975, the Lion meaning 925 Silver.
I don’t know what E.R. means for the Makers Mark?
I need help pinpointing the year. The date mark is a Capital C.
I also think the last satamp represents Silver Jubilee 1977 Queen Elizabeth II.
I don’t have photos just yet but hope to soon.

Hi there, thanks for joining us on
You are right in thinking its is sterling silver and made in Sheffield, the rosette mark replaced the crown mark for Sheffield in 1975 (due to the hallmarking act of 1973). The date letter for 1977 is a capital C for Sheffield, so if your bar has the monarchs head and a Capital C, then it is likely to be this year. (I can’t confirm this unless you post a pic).

Unfortunately I am no expert in modern silversmiths marks, so do not know of any E.R mark, except for E. Round & Sons, but they were a Victorian company, so I doubt it is them. If you post a pic I will do my best to find out who it is.

Hope that helps a bit.

Best regards