Thanks MW. The pics will have to wait till our spring visit, not having taken any to date.
If I only had a router and lots of scaffolding there's a lot I could do, but time is limited to about 3 weeks at a stretch, and that's without all the other stuff that needs doing and organising.
The house is from 1957, so the Master will be retired by now, if not deceased, and I'm not sure I can cope with all the probable blind alleys and diversions involved in asking locals who did the job - assuming I can use the correct phrases to ask.
You know how it is....
Thanks also MrMike: that would be a good way of fabricating a complete new moulding and I will bear it in mind if the job goes that way. At the moment it's more of a patch and fill exercise apart from one chunk.