I was careful not to state "in the centigrade scale", as I'm aware that the formula for conversion either way would then be (F-32)/9 = C/5.
I stated "the scale proposed by Anders Celsius".
The scale proposed by Celsius is the inverse of the centigrade scale, as he proposed a scale with the boiling point of water at zero, and its freezing point at 100


Nigel (I did state I was being a pedant!)