Once upon a time (and a very good time it was) the Abbey's Lady Gregory said: 'We went on giving what we thought good until it became popular'. No better motto could be found for theatrical managers, but how many heed it? The motto now is to give what the manager thinks will be popular until it is generally thought good. Hence The Mousetrap. It must be good because it has run for so long.

Agatha Christie's thriller has now been on for 21 years. It has broken every conceivable theatrical record. (p. 51)

What indeed does anybody know to explain the tenacity of this routine, country house whodunnit? (pp. 51-2)

[Whether seeds of immortality] are to be found in the text or the performance, the theatre or its position, its management or its publicity, is a question which nobody can answer for sure. (p. 52)

And it all began because...