I'm not sure, but the signature does look like Mrs Victory. There is no indication of a "Mrs Vicotory" signature in the Charlton, which leads me to believe that this note was originally unsigned. The "Mrs Victory" signature could have been added later, as graffitti, a joke? I don't know. Anyway, here are the values according the Charlton:
Unsigned Remainder: VG $135, F $225, VF $300, EF $400. I cannot tell the grade from the pic.
There are other values for two or three signatures which I don't believe apply to your note.
Hopefully someone out there will be able to shed more light on your note than I can.
Rarity is difficult to measure, but according to the Charlton, only 16,076 one pound notes were authorized.