There are a number of muncipal/public courses that have great bones.
I have played Camperdown, Dundee - now shut (but not Caird Park now knowing that's a Colt Course) and Hazelhead, Aberdeen (some Mackenzie holes) in Scotland.
In my area there is:
Thorpe Wood (Alliss and Thomas - mid 1970s) it was the longest municipal course then at 7100 yards - the expansion of the driving range reconfigured and shortened some of the holes still a strong challenge and has a high number of rounds of golf played.
Orton Meadows (Dennis and Roger Fitton - early 1980s) The front nine is potentially outstanding if it had TLC and some tree removal it is like transplanting a bit of Florida to Peterborough and the back nine is 1000 yards shorter with lots of par 3s.
Both public courses are run by Nene Golf. https://www.nenegolf.com/
Priors Hall - i have heard from local golfers that it has great bones and a challenging course better design than most private courses however let down by low costs towards maintenance.
Humberstone Heights - like Priors Hall has great bones.
Western Park - I had played it a few times in the Scratch League and thought it was challenging with interesting landforms and long par 4s sadly it is now NLE as council focused more towards Humberstone.
Also have a family friend who lives in Southampton says that Southampton Municipal is good course. It was originally designed by JH Taylor.
Municipal courses are key to the grass roots of golf and unfortunately in the UK its numbers are going downhill. Most golfers prefer to play courses with good greens and tees rather than judge it on the quality of the design irrelevant of the levels of maintenance.