I seldom venture into film criticism, but I suspect that like many men I was persuaded by my partner to go and see The Duchess, starring Keira Knightley. Looking at Keira Knightley is always a pleasure, but what a terrible script!

The credits list three screenwriters and an original book author, so you would think they might between them have got some of the period detail right. Unfortunately, in a genre of costume true story which has little but historical accuracy to justify making it at all, the entire film was an exercise in solecism.

Most fundamentally, it viewed Regency Britian through a prism of Victorian sensibility. The living arrangements of the Duke and Duchess of Devonshire were no more than very mildly scandalous by the standards of the time. In fact the Duke of Devonshire in question was pretty restrained in his sex life by late 18th century aristocratic standards. Nor was the menage a trois uncommon – this one was contemporary with that of Nelson and the Hamiltons. The attempt to project a modern sensibility onto a very different era was part of an attempt to draw a publicity parallel with the situation of a later Spencer female, Lady Diana Spencer. That commercial potential seems indeed the only possible motivation for the film.

The other fundamental flaw was the attempt to present the Duchess’ lover, Charles Grey, as a man of the people. He was played with a slight Estuary accent and there were several references to his lowly social stature and lack of funds; indeed his alleged dependency on the Duke of Devonshire for cash was brought into the plot at one stage.

What complete piffle. Grey was a senior member of the great Grey family of Northumberland and Yorkshire who people the Shakespeare history plays. He was born in their majestic seat of Fallodon and at about the time of the action of the film moved into his own superb mansion of Howick Hall. Almost all aristocratic families at this time led lifestyles that brought them into substantial short term debt despite their vast incomes, but the Devonshires were more renowned for this than the Greys. If Grey did have an accent (which he probably did – regional accents were more pronounced in aristocratic circles then) it was Northern, not London.

The film rightly connects Grey with progressive politics of the time, but errs ludicrously in trying to make him a working class hero. He was to go on to become the Prime Minister who forced through the Great Reform Act, the first and most crucial step towards British democracy, and the abolition of the slave trade. The tea is named after him. The family were always connected with the progressive side in politics. A Grey was the only member of the House of Lords to sign Charles I’s death warrant. Stephen Grey, the best exposer of extraordinary rendition and author of Ghost Plane, is a member of the family.

Back to the film. Among the scores of the easily avoidable mistakes, the use of titles was wrong more often than not. Grey tells a grieving Duchess: “I am engaged to Lady Ponsonby”. That would come as a hell of a shock to Lord Ponsonby. He meant he was engaged to one of Lady Ponsonby’s daughters, and would in fact have said “I am engaged to Lady Mary Ponsonby”, or much more likely between these two, just “I am engaged to Mary Ponsonby”.

Anyway, “The Duchess” is a lot of unhistorical bollocks written by the terminally ill-educated. It would have been much more enjoyable just to watch Keira Knightley sitting quietly for ninety minutes.