Pan F & FP3 - 18 minutes @ 20C
Continuous agitation for the first 10 seconds then 5 seconds every minute.
Gives 1 stop more effective film speed
Information about ILFORD Perceptol tends to suggest film speed is lowered so it is interesting that this developer apparently gives a 1 stop increase in effective film speed. At first consideration, I'd have thought exposing Pan F Plus at E.I. 100 would result in rather high contrast.

Tom