What does a celtic cross like hallmark mean?

[ptree]

Hi, I bought a silver bookmark recently. It has 4 hallmarks on it. I know that the one above ("DP") is the marker. The right one below is the Year (1988). However, I could not figure out what the celtic cross like hallmark on it mean. It is the middle of the three hallmarks below in the image. I would be so grateful if some experts would be able to identify it for me. Thank you so much in advance.

Image is here:
http://www.auctiva.com/hostedimages/sho ... 0&format=0

[rhodrit]

Hello, its an import mark (for the london assay office i believe but dont have my copy of bradburys with me) because the piece has been imported into the uk,
Rhodri

[ptree]

Hello, its an import mark (for the london assay office i believe but dont have my copy of bradburys with me) because the piece has been imported into the uk,
Rhodri

Thank you so much, Rhodri. Your answer helps a lot.

[silvermakersmarks]

I can confirm that it is a London import mark. For anybody who is curious about the symbol, it is the astrological sign for the constellation Leo, chosen perhaps because Leo and London both begin with the same letter (?). As it is an import "DP" is unlikely to be the maker, but rather the importer. The correct term for the mark, "sponsor's mark", therefore makes sense in this context.

Phil