Mason's work (at Ilford) complimented G.I.P. Levenson's (at Kodak, Harrow) and it's no co-incidence that Levenson was the editor working with Mason on his book.

The years old extremely heated debate on etc was based on incorrect assumptions, Levenson's work at Kodak was on washing after Sodium Thiosulphate based fixers often with a hardener, while the later Ilford wash technique is based on Ammonium Thiosulpahte based fixers (Hypam) with no hardener. A fact conveniently over looked by both sides until Roger Hicks pointed it out.