And lo, there was rack.

And Shaggy saw it was good, and did grin :-)

A bit of a faff to fit though, the front legs needed spreading by about 3/4". Percussive maintenance with large persuader (number 2) and a handy concrete bollard later, sorted. I had to drill the shock absorber mount out slightly to accept the new 10mm bolt too, the old one being 3/8" (9.5mm)

Rack is part number 92541, from Hitchcocks :-

http://www.hitchcocksmotorcycles.com/accessory-frame-luggage#part_4341