In reply to Postmanpat: Is this the Directissima we are talking about? Mandella?
I have a slight input in to the history of this, Ron Fawcett led the first pitch, on sight and on situ gear. At the belay we had an argument about whether it was HVS or E1 (my vote was for E1) I think today it is E3, or some blundered down version which is a sport route.
When we got to the top of the first pitch, Ron looked out along the roof and said
"You know Al, this might go free"
He proceeded to do a couple of moves that became Mandella, then came back. I am convinced that if current ethics and the bolts had been in, Ron would have done Mandella in 1975. Though I refused point blank to second it. I offered to film an attempt which he was considering on situ gear.
Point is, there are many routes still on aid in the UK where it can be practised, no need to risk damaging a great free route by aiding it.