raden wrote:

Valiant

No, it's Valliant ...

according to the rather large window display for Gas Mk1 in Watford

I've found that most plumbers/CORGIs pronounce it as 'Valliant'. If you
pronounce the word as 'Vaillant' they will usually add extra emphasis
to the word when they next use it. 'VALLIANT' they'll say to correct
what they perceive as your mispronunciation.

The Gas shop have it written as Valliant in their window because the
CORGI installers they deal with talk of Valliant boilers.

Which makes me wonder whether I really want such people working on my
gas installation. RTFM? They haven't managed to read the box, despite
claiming to be 'professionals'. Which they're not.