The queen of crime has not always received cinematic treatment appropriate to her status. The earliest Agatha Christie adaptations were quota quickies, made when legislation favoured fast cheap films from British sources. Even the much-loved Margaret Rutherford Miss Marples of the 1960s tended to play at the bottom half of the bill.

Today we expect something more regal. Sumptuous and frequently exotic surroundings. Stars, often in eveningwear, lining up to dazzle, and then being slain in a variety of imaginative ways. This precedent, however, was not set by Kenneth Branagh’s current all-star Poirot spectaculars. Four decades ago, Christie was providing material that answered the demands of audiences hungry for classy spectacle – and those of producers eager to provide it at the right price. Her fiction was ideal. It featured large groups of characters that might attract big names in search of short and pleasurable job with lots of on-screen cocktail-bibbing. Her plots were sufficiently malleable to allow the possibility of filming in locations with favourable tax regimes. (Evil Under the Sun was relocated from Devon to the Balearic Islands, where director Guy Hamilton lived beyond the reach of the Inland Revenue.)

The result? Gorgeously decadent entertainments that gather casts that would be impermissible under any other circumstances. Where else would you find the passengers of Murder on the Orient Express – Albert Finney, Lauren Bacall, John Gielgud, Sean Connery and Ingrid Bergman – beyond a daydream or a memorial service? And when Diana Rigg and Maggie Smith stand at the piano in Evil Under the Sun for a competitive version of Cole Porter’s ‘You’re the Top’ – to applause from James Mason and Michael York – it’s clear that they, like us, are at a swell party. It doesn’t matter very much if someone’s drink has a suspicious tang of bitter almonds.