Why should it be "a very different matter"? Surely what's sauce for the young goose is sauce for the older gander? He or she might as well argue that "in 1999 for heaven's sake" it's quite all right for a young man to be a drunken driver, but totally reprehensible for a man over 50 to be one.
Such an argument is utterly hypocritical and ageist, apart from its complete lack of logic. Why is a teacher of 50 to be condemned for "abuse of power" in having a senior pupil for a lover, but not one "only" 27 years old?
I find the letter disgracefully prejudiced, and the correspondent's anonymity telling, but he or she does illuminate why, as a general principle, sexual relationships, however loving, between pupils and teachers, and whatever the age gap, tend to undermine public confidence in teachers, and rightly so.
(Dr) M Relich
Allan Park Loan, Edinburgh