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Maybe, but I doubt it... But I may be wrong.
Huh, I didn't think pitot tubes needed any kind of pressurisation system to power the speedometer, which it sounds like might be what's going on here if I've understood you correctly.
I think I remember reading that the early production Swordfish Mk I had an unheated Pressure Head (ie Pitot Tube). Later production received a Mod that introduced Pressure Head (Pitot Tube) heating. The Mod number I read about was a lower (I think) number than 318, but there may have been more than one Mod number for the same thing depending on the Swordfish Mark and the already existing equipment and/or other Mods.
I have read other instructions where mention of an aircraft's Pitot Head heater being turned on before take-off.
Maybe?
Yeah, I'm thinking the label for the right-most switch would read "Pitot Head", not pressure head. Mosquito B.35:
View attachment 771377
Maybe the Swordfish flew so slowly that there wasn't enough air pressure into the pitot to work the instrument, so additional pressure was needed. -- just guessing.