Thanks Ian that would be very helpful. I phoned Astrali and they said they only make 9 hole, I said I have a 6 hole boss with Astrali name, patent stamped in it and he couldn't comment!
Clive, I might join your club! I'm waiting for Mountney to email a drawing of their Vitesse boss which shows a 6 hole and if it has the pencil hole it could be a correct solution.
Iain