LAST WEEK English National Opera announced details of its April to July season. Of its five productions, two — a revival of On the Town and a new Kismet — are musicals.

The ENO’s On the Town is wonderful. Kismet will doubtless be equally terrific. But their quality is irrelevant — it is wrong that ENO is staging them at all.

ENO receives an annual £16.5 million Arts Council — read “taxpayer” — subsidy. The point of a subsidy is to make good so-called market failure; to provide that which the market will not. So the three other operas in the ENO’s season — Death in Venice, Satyagraha and Clemenza di Tito — sit perfectly properly in the schedule.

On the Town and Kismet, however, are archetypal Broadway musicals that can, and should, exist without the need for you and me to hand over our money to the Inland Revenue so that the Arts Council can pay for them to be put on.

That there is a difference between opera and musicals is shown by the latest opening at the National Theatre. Confusingly, while ENO has decided to stage two musicals that are not operatic, the National Theatre’s new production, Caroline, or Change, is an opera in the guise of a theatre musical.

The story of a black single mother’s relationship with the liberal Jewish family who employ her as a maid in Louisiana in 1963, Caroline, or Change is moving, intellectually engaging and operatic in its themes. Commercial or not — its US production managed 159 performances — it is a stunning piece of work.

Many operas — The Magic Flute, for instance — fit the description of a musical, with large amounts of spoken dialogue, comedy and show-stopping numbers. Many musicals that might seem operatic in their sweep — such as Les Misérables — are meretricious trash. And some musicals — Showboat, for example — deal with the deep moral issues that are the concern of many operas.

In the end, the difference between opera and musical comes down to the old saw: if something looks like a duck and it quacks, chances are it is a duck.

But we know one thing: an organisation that depends on taxpayer subsidy and exists to stage productions that would otherwise not be possible has no business putting on musicals that need no subsidy from anyone.