I`ve done this before: Remove the soffit inside the barge board and if the battens are exposed, fix the slates using copper wire. Very fiddly, not an easy job.
Tony gardner, May 2009
As they cannot be nailed you need to make up out of galvanized wire a slate retaining hook or ask in builders merchants if they have ready made ones.
You might need a 'Slate nail ripper' but check first with one of the new slates push it up in position if no nails on any missing areas save money hiring the ripper for nothing.
Hook wire over batten leaving at least a 2inch longer than the slate end this will form the up turn to hold the slate in place. You need a pointing trowel to make it easier to remove any you put in that need moving down again slide the trowel under the slate push down with other hand the slate onto the trowel and pull the trowel down and the slate should come with it.
