“One thing is certain: once a beer of a particular character has found its market, it is important that the uniform standard be maintained; and it was no doubt with this in mind that an old and wise craftsman is said to have given one last piece of advice to his pupils. He said to them, ‘If when you take up a new job you find a rat in the mash-tun, leave it there. The customers may like the flavour!’”
Sydney O. Nevile, Seventy Rolling Years, 1958.
(PS. Note that usage of ‘craftsman’…)