Almost 52 yrs ago(13/8/70) I was `co-opted `to fly as co-pilot in XB261,at AAEE with Capt `Jake `Wormworth,RCAF/CDF Exchange pilot on `B`Sqdn,to fly an ULLA drop on Salisbury Plain.It turned out to be the heaviest ULLA ever dropped,so I think it was well over 30K Lbs.I can`t remember whether it was multiple pallets,or one single large load.However,on `extraction` as the load moves aft,so does the C of G,and this will lead to significant pitch inputs.Not only that ,but the`drop height` has to remain constant at about 10 ft wheel height,using the radar altimeter.Now the `run-in`approach to the DZ that day was not very flat,so I was in `charge` of the engine-room,over 10k Horsepower,to maintain airspeed,and height,as Jake pushed/pulled the control column,whilst also `conned` by the Navigator in the lower-deck aimers window.We did one `dummy` run just to make sure we were all on the same `hymn-sheet`,and then the final drop,which went as planned....but it was 30 secs of `full and free` controls by Jake....Fortunately ,the Bar in the OM opened early for a few `refreshers afterwards`...