Sorry Andy !
Yes Alberto, I've seen a few models with the hatch like that - lack of research on the part of the modellers.
The hatch was retained in the closed position by two pins on the bottom edge, and by the canopy over the rail on the top. The red handle released the pins, and with the canopy fully open, the hatch could be pushed clear.
I've read at least one account of the hatch flying off in violent manouvers, departing with a loud bang !