Dragonfly Frame Number

[mikkings2]

Gents,
            Checking over my recently puchased 1957 Dragonfly checking for a frame number, have looked closely below the LH swingarm pivot which is where I understand it is located and can see no sign of it, the V5C lists the number on the top RH side of the gearbox as chassis number, surely this the gearbox number? Any ideas?
Thanks Mike

[mikkings2]

Gents,
               Took advice and scraped the paint off the gusset plate, found a number.
Thanks
Mike