This reminds me of an excerpt from Niki Lauda's autobiography. He recalled a time when a certain internal route was operated by AUA using a Metropolitan which the pax nicknamed "The terror tube". Lauda operated a Fokker 27 in competition with AUA. AUA repsonded by sticking a DC-9 on the route. At a function which Herr Lauda attended an elderly senior manager from AUA came up to him and warned that [in the Nazi period], non-conformists were lined up against a wall and "rat-a-tat-tat", but these days, they'd have to do it by putting him out of business.
As a follow on to this, I've received a reply from the Global CEO and he's agreed to up his prices by v$5 on flights operating out of Birmingham. It does seem that he was getting extra revenue (to the tune of one bod per flight) by using lower prices but he was unaware that all the other airlines were losing a fare as a consequence.