In reply to Silverdene:
For heaven's sake, when did this actually become a problem? I entirely fail to see the need for it - standard practice for an under-sized second is for a third party to grab a handful. Stumbling around in the vegetation to find a suitable spot is going to damage it and I disagree that screwing one of these into compacted sandy soil is going to have negligible effect.
Stone Farm is an SSSI for a start - and what you are proposing/have done contravenes at least one of operation references 12, 21, 23 and arguably 27 in Stone Farm's 'List of Operations Likely to Damage the Special Interest'
Stone Farm is vulnerable - the soil level beneath 'Thin', for example, has fallen by 9 inches in three years and, if any more bits drop off as they did a few weeks ago at the left hand end of the crag, then op ref 27 is waiting for us (Recreational or other activities including rock-climbing, likely to damage natural sandstone crags)
As far as two krabs at the top instead of one, I'm pleased to stand corrected, but I would have thought that running a rope over more metal woudl increase friction, but maybe not.