In reply to UKC News:
I know of three experienced climbers who have failed to tie in and check their knots.
1) At Malham, climber clipped into lower off and decked it breaking both legs badly.
2) Climber had only tied into 1 of his double ropes, he took a very long fall with no injury.
3} Climber on Dangler on Stanage did not tie into either double rope, ropes fell from harness half way up, he decided to carry on and made it to the top solo.