Blenheim flaps.

[Herra Tohtori]

The Spitfire had pneumatically actuated flaps that were either up or down. There was a single switch that controlled the direction of air pressure on the flap extension system, and it would either lower or raise the flaps depending on the position.

Careful juggling of the flap switch would theoretically allow you to keep the flap in certain position.

The Hurricane had hydraulic flaps with an actuator valve inside the cockpit directly controlled by the pilot. By setting the valve to "down" position the flaps would move down, setting it on middle position would stop flap movement, and "up" position would raise the flap. The same hydraulic valve controller was used for the extension and retraction of the landing gear. To select which function you wanted to control you would move the lever left or right through the middle position.

So, in Hurricane you couldn't lower or raise gear and flaps at the same time!