New lock arrived today. One week from Germany, not sure if that is good or bad but it got here.
Out with the B&D to drill the old lock, fitted quite easily so all sorted.
The eBay listing I bought from offered 'A guide with photo' on request, so I requested - a bit more guidance couldn't go amiss.
Not sure that it added much, and I don't think I would recommend risking using one of the new keys to help remove the old lock!
So this is what you do ....