Experience is a wonderful thing.
Dropped the sump off, to discover that it was actually the filter tool slipping on the filter.
Hmmm okay, so the filter must be on far too tight ( the book lies)
Undo the stuck filter with chain grip ( yes, knackered the filter )
Oil the seal and fit new filter, as tight by hand as i can possibly get......undo filter with torque wrench to estimate the torque setting of "hand tight", My hand tight is 10nm.
Wrote that in the spec page i found online for next time.
Definitely replace sump gasket, they are cheaper than a leak in the middle of nowhere!!
All good to go.