I developed my back up negs tonight with the following scenario
FP4+ presoaked in distilled water for 5 mins
developed in Pyrocat-HD 1:1:100 @20C for 13 mins (N+1) in BTZS tubes
stopbath 1min
fixed 5 mins
washed 25mins in running water.
The resulting negatives are superb. Lovely contrast and detail but the negs are definitely PINK. The presoak water was purple with dye and there is no sign of any dye left in the emulsion. I am happy with the negs but would like to know why I don't get the brown shift that you all enjoy.

Phill