I have got in touch with a potter in Cheshire and sent her photo's of the said scuttle and bowl, and i await a reply, I shall keep all informed as to progress.
Fozz, I do think that the temperature of the water is an issue. There is a view that boiling water is too hot and will degrade the lather after the first pass. But tap water that is not hot enough is not much use. I guess a little experimentation is all that's needed. Mine seems about right. I just like a bit of warmth, and that's what I get. Both for the brush scuttle and the 1.5.