603DX
You could not mistake the Swing type ejection seat ,we used a 'Pig Sticker' to hold the control column forward,this allowed the bang seat to swing forward to the fwd latch,the nav would get in - then the seat was swung back to the rear latch and the pilot(s) could enter.Once both pilots were seated the seat was swung back to the centre latch and the 'Pig Sticker' would be removed.
I have seen a drawing somewhere of the seat that you describe...but of course all T4s would eventually have been modified to have bang seats.
rgds baz