There’s a superabundance of sparkling, often marvellously terse one-liners (when asked what the “O” stands for, Thornhill’s resigned and emotionally relevant answer is, “Nothing”) – and, my, how wittily Grant delivers them.

This is Hitchcock's longest film and also his most self-referential. Little jokes abound about art and artifice, role play and reality, duty and duplicity and each viewing reveals something new to enhance the pleasure of watching the Master of Suspense at his most mischievous and assured.

This film is pure entertainment.

The picture is hugely pleased with itself, but it’s too funny and expertly calibrated to mind in the least. Both Hitchcock and Grant raise relaxed confidence to masterpiece level here.

[A] sublime classic.