Depends what you call NR tracks. There is 18006 at Crewe Basford Hall, and haven't there been two at Eastleigh?
Last I worked out and I think still correct :-
18002 Loughborough Brush,
18003 Scunthorpe Steel Works,
18006 Crewe Yard for Freightliner,
18007 Tunstead (appears to be on private sidings),
18012 Whitemoor Yard,
18014 Eastleigh Works (was Eastleigh Yard) and
18015 Eastleigh Works (was Eastleigh Yard).
I think some of the above were for GBRF.
The remaining eight are awaiting deployment at Wolverton.
It now looks like they (over 50% of the class) will be in mint condition for any prospective buyers !.