In reply to jamface: Two possibilities - contact the factors, or contact MCofS as someone else suggested.
The factors have an office in Charlestown itself - to the left of the Elgin hotel, opposite the village green. They are quite hands-on and would probably be employed by the estate to do the work if Lord Elgin were to get ask for it.
The last round of access problems were solved partly through MCofS. Whilst this isn't an access problem in itself it might be worth getting their advice on what to do: hebe@mountaineering-scotland.org.uk