Use plenty of solution, agitate for 5 minutes and let it stand for 6 hours at 24 degrees C.

Apparently it’s called DD/FF (dilute developer/fast film) and was used by some press photographers when they found themselves in low light situations without a flash. McLean was told to expose Tri-X at EI 400, 800 and 1600 on the same roll of film and use this technique.

When I tried it I got rather strange but usable and sharp negatives from EI 400 – and a very dirty Paterson reel.