It is not surprisingly that difficult to do, not that I ever done it with a Bell rope. But as most of us who have been 'Brussel Sprouts' [Scouts] especial Sea Scouts. It was part of training to climb a rope & be able to put a sheepshank in it, with one hand, while holding on above the knot with the other. Well it was when I was a young .
I could only do it these days using a Tallascope or Genie lift. We also could do this tyeing other knots such as the Bowline on a Bite or a Running Sheetbend, again using one hand.
These days of course I doubt it is part of their training, because of OCH&S concerns.
Disclaimer; Do not try this this unless you are suitably trained & are secure wearing a fall arestor harbess &/or least well insured!
But I do remember falling a number of times before I got the knack of it, as it was only about 6' off the deck, so you learnt very quickly to be able to break fall.
Which came in handy back in the 70's when I did about 3 or 4 break falls per performance, down stairs & off the top of rostra, in 'Irma La Douce', at the Old Theatre Guild in Hay street Perth.
Try tyeing the knot with one hand Craig it is not that hard to do, but you are allowed to climb the rope using both hands, also besides holding on with one hand, you can use your legs to wrap around the rope, which helps with looping the rope.
