Possible crown derby but no colour in mark

I work in an auction house and part of my job is to identify items that come in to the auction either for valuation or to sell. I have had a plate brought in and the logo looks like a crown derby mark but there is no colour to the mark, to my eye it looks like a crown of royal crown derby with & Co under it. Below are some pictures that may help I have shown the design of the plate as well as the mark below. any help on this matter would be much appreciated.