In reply to David Alcock:
A quick look at The White Spider gives the following: "There were other ropes on that part of the face during those days; they were Werner Hausheer and Paul Jenny, making the thirty second ascent while Robert Bogli and Willy Motter were making sure of the thirty third. Not one of those four Swiss, nor anyone else saw a sign of Carruthers and Moderegger. They must have fallen off on August 30th"
Egon Moderegger was Austrian while Tom Carruthers was from Glasgow. Neither apparently spoke the other's language. Carruthers had partnered Brian Nally on the North Face of the Matterhorn. They started at the same time as Bonington and Clough but couldn't keep up with that team's pace.