We filmed most of the story on location in Ilkley and Barnoldswick, happening to find in the latter place an empty parade of shops with, as a centrepiece, a disused cinema. Many of the countryside scenes are in Wharfedale around Bolton Abbey. Sutcliff’s farm was Laund House, an idyllic spot above the Wharfe where Beatrix Potter used to stay, the kitchen garden still overrun with rabbits but with no Mr McGregor to say them nay.

Betty was played by three different pigs, not in order to comply with the requirements of Equity or the RSPCA but because each pig had different skills. One was a good runner but shy in company; another could climb stairs but would not sit still; and the third, while much the most photogenic, had a black patch on its back that had to be painted out before it went in front of the camera. The lynx-eyed continuity buff will note that Betty may seem to vary in size from shot to shot. She does. The only way to persuade the pigs to perform was by constant feeding; they therefore grew at an alarming rate. Since the film was not shot in sequence this can mean that Betty is quite portly in one shot, suddenly slim in the next.

There are obvious hazards of working with a pig and they are not all that different from the hazards of stealing one. Toilet training is not their forte, and one of the unsung members of the unit was an unemployed Ilkley boy whose job it was to follow Betty round with a bucket and kitchen roll. The slightest quiver of the porcine sphincter and he was there poised with his pail. It was his first job in Mrs Thatcher’s New Model England and he deserves a credit with the director and the stars.

There is no such thing as a good script, only a good film, and I’m conscious that my scripts often read better than they play. Of some scenes in A Private Function this is certainly true. It is easy to write ‘The pig smiles’ or ‘The pig trots dutifully after him’ and quite another to persuade the creature to do so. So in any scene involving the pig the script tends to be a statement of intention rather than a description of what actually happens.