Thanks PhotoJim - As I mentioned, it's FP4+ (4x5).
On looking at the neg again and putting it beside negs not developed in pyro, the stain is a bit more obvious. Overall, it's a sort of straw colour, including the film edges, but it doesn't seem very intense. Perhaps it's just a matter of me not knowing what to expect.
I have read about the afterbath being no longer recommended, so might give that a miss in future.
I don't usually presoak films, but Hutchings gives it as a means of avoiding streaking, so as this was my first attempt, I thought I'd better follow his advice. Certainly the neg seems to be free of any streaks or unevenness.