Whilst there's talk of sitting backwards in MKIII's I was told this story from a reputable source which stopped one VGS from doing this further and probably a few more if they had known!
The story goes....
P2 sat backwards with a camera to record the event. After launch P1 entered a series of severe aerobatic manouvers ( stalls and dives) which P2 considered was a little sporting whilst he was trying to take photos. The aeros finished at a low height followed by a prompt landing.
What happened? Well during the launch the rear seat stick ( held on the backstop in true pole bending fashion) got hooked underneath the straps holding in P2 ( he was oblivious as facing the rear!). After launch P1 couldn't prevent the glider from stalling and diving with each manouver getting worse than the previous as the stick was stuck fully back. By the grace of god and at a low attitude during the reduced 'g' of one of the stalls, the straps went slack and released the stick!!!
As i say this story is second hand to me but I have no reason to doubt its authenticity!