Originally Posted by
sharpend
It does not. The Bulldog indeed has a Both position. The fuel selector in front of P1 (in an RAF Bulldog) has L, Both, R and Off. As a matter of interest, if you leave the selector is Both with the aircraft on a slope you will rise fuel being syphoned from one side to the other.
The Bulldog was approved to an old UK Military standard, AvP970, which had different philosophies behind it compared to the current civil aircraft standard CS.23.
It does surprise me that CAA allowed transfer of ex-military Bulldogs onto CofA without modification of that valve, but they did - JAR-23 would have been extant at the time, and that certainly never permitted a "both" setting on a non-gravity pumped 2-tank system, any more than its successor CS.23 does.
G