Hmm, seems this one is actually B115 HOP with some dodgy spacing. B15 HOP is listed as being on a Maestro van, while 815 HOP is on an S Class belonging to, surprise surprise, a Mr Bishop.
North London financier Warren Steingold, who also owns (or has owned) CO 1, LF 1, OW 7, PP 11, X 11, 11 JR, 11 KE, 11 MJ, CLE 1N and GRE 1R. Phew!
Neither: seems it belongs to a lady from Harrogate... called Nettie.
1 T (along with various others, including 1 MB) belongs to Trimite Ltd, and is shown as being on a BMW 7 series, which somehow seems more plausible. Might have been a butchered number that you saw.