Set the sag to 10mm by increasing pre-load on spring.Attach R.H.T,back wheel hanging measurement top of nut,top of tool=239mm+21mm axel centre = 260mm.Is there enough adjustment left on the tie-rod to get down to 245mm?.Or have I got this wrong.

Something doesn't sound right. I can't believe you're running a 260 mm ride height with the rod at the near shortest length.

Ride height now exactly 245mm.224mm top nut /top of tool+21mm.Tie rod at its shortest length almost,the only non standard part is the spring,which is a Maxton item as the standard spring was way too stiff for my weight.
Measuring from top of spindle nut to fixed point:-
Bike back wheel hanging =443mm
Bike on paddock stand = 433mm
Bike plus my weight = 400mm
Does that seem about right:puzzled:

Not to me it doesn't, sounds as if there is to much loaded sag, can't be sure with out checking a few figures and having a bit more info,
Do you know what spring rate the Maxton spring is, what is your body weight and was the measurement taken with you in a prone riding position.

just thinking along the lines that 33mm of sag is approximately 16.5mm of shock travel and if the spring is say 7.5kg/mm then thats a few Kilos needed to move the shock that far especially when you allow for a front to rear weight bias of around 50/50

Thanks for the comments so far,Im not sure what the spring rate is,had to wind on a fair amount of preload to get 10mm static sag. Im 71kg sat upright on bike when mesurements taken.Im confused as to calculating loaded sag,is it the difference between the static sag and rider or unloaded +static+rider,in my case:-
Static measurement433mm,+rider =400mm Loaded sag 33mm.or
Unloaded443mm,static433mm+rider=400mm Loaded sag 43mm.
Most of the web set up guides suggest 30-40mm loaded sag,am I that far out?