I've got an obscure guess, but it's only that. i started by looking for london-based pipe mfrs of the time (1910-1915) consisting of partners whose last names began with "d" and then "c". zilch. then i began looking for silversmiths. here i struck tin. in 1910 there were two neighbors on tottenham court road: james dodimead, of 50 tottenham court, sold electrical accessories; and william campbell, of 40 tottenham court, was a jeweler. in the 1911 census campbell is listed as retired, and dodimead is listed as a jeweler. in 1914 william died, and in the post office directory issued later that year james dodimead is listed as "dodimead, james (late william campbell), diamond merchant, goldsmith, silversmith & jeweller. 40 tottenham court"
so if you want a very longshot guess, here one is: william campbell retired in the years immediately before his death, say 1911-13, and at some point he passed the business and its premises along to his neighbor james dodimead; perhaps during a brief transitional period the business was called dodimead & campbell, and utilized hallmarks that read d&c.
that's an awful lot of supposition to load onto one little pipe, but for now it's the best i can do. i can think of several reasons why this might be a false trail, but it's worth thinking about all the same. unfortunately as jesse said information regarding uk silversmiths and their hallmarks is scattered around many places and a theory like this can be hard to prove (although a book by john culme is very helpful, if difficult to find).
in any case it's a beautiful pipe and a remarkable find!
:
