I recall the seats at the rear of the Nimrod were built in as a troop carrying requirement and the original negotiations included the bird brained ability to drop parachutists through the rear door. There was a serious disarmanent group within the labour movement and the multi purpose plan was the only way to get such an expensive design through the left wing loonies. (Michael Foot, Harold Wilson and Dennis Healey come to mind, although others may have a better idea.)
I remember there were reports of one, repeat one, brave soul who rolled out to prove the concept. The port engines had to be shut down, and the parachutists only just missed the tail. Unfortunately I have no verification of this, but will double check.
Keep in mind the MR1 was a mismatch of ideas, systems and suppliers. The computer came out of an army tank, the radio from the canceled TSR2 and the whole concept was half-assed. It was sold to HMG as an unarmed reconnaissance platform, with nuclear weapons. How the Soviets didn't shoot it down and start WWIII was amazing in hindsight. But after the Shackleton 3.3 it was sheer luxury, and an occasional ATU fire was worth the comfort.