Interestingly, my fill-in dentist was a very nice young woman from Poland. She only asked questions while she was looking me in the face and offered an alternative to an extensive drilling and refilling procedure. It was a concentrated fluoride solution painted onto and around the tooth in the hopes that it would continue to settle down. There were no signs of major trouble externally and it may be that this will be sufficient. If the problem recurs then a filling is the only option. The problem is that there is so little tooth left that I am not confident of success.
Oh the trials and tribulations of having grown up during and after the Second World War!