hello
look at
http://www.925-1000.com/dlLondon.html and compare the maker's mark as well as the shape of the cartouche with yours. If they match in all respects, it not only is London 1879, it also is Charles Edwards.
Important to remember: there may be numerous
similar sets of initials, but in order to establish the identity of a maker you have to verify the marks in their entirety, i.e. the letters have to be not similar but identical, serif matching serif, etc; the cartouche must be identical, or it must match a known variant, the date letters, duty marks etc also have to match. That being said, there still are oddities, many of which are explored via this forum. The huge majority of marks, however, follows the accepted pattern.
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