Been trying to identify this one for years.
- Live-action UK TV miniseries in maybe 3 parts, on commercial broadcaster (almost certainly ITV at that time but might have been specific to the regional broadcaster). UK production in English.
- 1980s, probably earlier rather than later
- Main character, single Dad with I think a nanny/friend looking after the child. Played by an actor I knew from somewhere else, maybe had been a TV detective or such but not very famous. Was fairly rich due to a successful business he and two friends had started in their youth.
- Gets involved in strange situations and is trying to solve some puzzles to find the answers - seems to be several people working against him.
- I remember a "medieval style" banquet at a castle, don't think the protagonist was actually at the banquet, he ended up getting locked up in a tower in the castle, met a Jester character who was initially seen as trying to help him.
- The scene I remember most clearly was him working in his office at home on a puzzle about a set of mysterious symbols. A woman who is suspected of being on the other side comes by to talk to him, pushes a paper onto the symbols so you can clearly see they are mirror image numbers (like these) *1
- The denouement was set at an indoor swimming pool and it was revealed his female business partner (correlating to the Lady of the Lake) had died and it was the male business partner he had cut out of the business who was doing all the issues as a Merlin figure to make him acknowledge something about it.
- It was only in the final episode that any of the Camelot references became overt - prior to that it was all just mysterious with possible medieval references.
Note: It is not any of the Arthurian works listed in Wikipedia and I have tried rummaging through IMDB many times, nor can my Google-fu skills detect it as any reference to Camelot gives me way too many other productions.
*1 - the reason I remember this scene so clearly - the show cut to a commercial break at that point and when the action resumed, he just tidied up his papers and lost the clue she had tried to give him. I felt that was cheating.