petrol tap identfication

[Wayne]

Hi all Dose any one know what bike and year the petrol tap in the picture was originally on, it was used by Norton on the late 88/89 screw top filler Spondon tanks (Stuart at Spondon cannot help). Its flange mounted with side outlet and the tap on the bottom. The picture was taken with a endoscope in the museum through the triangular hole in the seat and why the quality is not good. Any help is appreciatedRegards Wayne