A year later with this tank bag review:

Givi EA123 Tank Bag
Constructed from polyester 600D PU
Convenient Tanklock fitting
5 litre capacity
Zipped front pocket
Rain cover included
Detachable shoulder strap

Fitting kit sold separately but bag link below, they also sell the fitting kits:

https://www.sportsbikeshop.co.....uk/motorcycle_parts/