Is it unreasonable to expect a live performance of a play to follow the script exactly? Surely, only robots can be word perfect every time, and does it really matter if Portia says 'The quality of mercy is not strain'd/It droppeth like the gentle rain of heaven/Upon the place beneath' (William Shakespeare The Merchant of Venice Act Four Scene One), instead of … 'it droppeth as the gentle rain from heaven…'. Shakespeare's works are so famous that there would be bound to be someone in the audience who would notice, but for most plays it would make no difference. It would be churlish of any playwright to object.

Not all changes are accidental slips. It might be that the language is updated for a modern audience to understand, or that attitudes or the action is altered to make it relevant in today's world. Comedies, are particularly susceptible to this as humour can rapidly become dated, or once notable people who are the butt of the jokes become forgotten. Using Shakespeare's work as an example once again, can there be any recent production of A Midsummer Night's Dream that hasn't cut a large chunk of the exchange between Puck and Fairy at the start of Act Two? It just isn't funny now.

But at what point do necessary changes become gimmicks or the result of a director's personal foibles? Are these still okay or are they taking unwarranted liberties? What if they alter the essence of the play? When the production of A Midsummer Night's Dream that I saw at Birmingham Repertory Theatre recently made the action take place after Oberon had stolen the changeling, and made Puck a servant of Titania, who places the love enchantment on Oberon's eyes on Titania's orders, it changed the whole relationship between the characters as well as many of their lines. Of course, Shakespeare isn't around to object, but if he was, would he? He obviously hadn't intended to put a woman in control, or make a man the victim. It raises questions about the interpretation of the play, but does that make it valid?

I'm not Shakespeare, and I don't regard my lines as sacrosanct. In the productions in which I've been involved, I've been happy to improvise a little and ad lib where necessary. Because I was involved, I could give my approval. Although not word perfect, the resulting performances retained the characters and spirit of my play, which was what mattered most. Performances are living things, after all.