Ed, there was a TV program on just recently, King and Country iirc, that showed the original hard shelters that the V-1 used. The item mark 'Q' looks like the curved assembly building (camouflaged). One end of 'Q' is at one end of 'P', so would hazzard a guess and say 'P' is the launch ramp.
http://www.bunkerpictures.nl/datashe...on-cappel.html
The pic on the left is the launch ramp.
http://atlanticwallbelgiumboulogne.1...siracourt.html