I got it working!
Not with extGPS
but with a beta app called GPS Over BT
, I took some screwing about but it WORKS!
I now have a 17 inch chartplotter
... All I need to do now is download charts
for the entire world.
I feel like I'm living beyond my means a bit!
If anyone wants to know how to do this let me know, I think I could do it again and I am fairly sure that it will be a LOT easier the second time.
Thanks Sinbad, for some reason your post gave me the kick in the rear I needed.