After the surprise of the Royal Shakespeare Company’s new witch-free production of Macbeth at Stratford, we have from Oxford Theatre Guild, by contrast, a version of the Scottish Play in which the Weird Sisters are supplied in triple the usual quantity.

I write deliberately of a ‘version’ to suggest a deviation from the original, which is what is here supplied in various ways under co-directors James Reilly and Jessica Welch.

One of the strangest changes is to get Macbeth himself — played with increasing confidence on Tuesday’s opening night by Peter Malin — to utter the witches’ warnings he receives in his final meeting with them. This, I felt, seemed likely to cause confusion to the many young members of the audience seated around me in a leafy (and chilly) corner of Trinity College Gardens. But the rapt attention of the full-house crowd appeared to indicate they were taking it all in — well, perhaps not quite all, since competition from traffic and nearby roisterers drowned out some of the dialogue.

The affecting exchange between Lady Macduff (Cate Field) and her son (Daniel Taylor) at the castle of Macduff (Mike Taylor) was almost completely lost. It is another odd conceit of the production that Macbeth is present for the slaughter here.

Some of the characters are plucked from the swollen ranks of the hooded hags — including the bleeding sergeant, the drunken porter (whose familiar speech is passed around the nine-strong group) and the third murderer. The last turns out not to be a murderer at all, for Joe O’Connor, who plays him, is given Banquo’s line instructing his son to “Fly, good Fleance, fly”.

Fleance himself is a bit of a surprise — not the usual child or adolescent making a brief appearance but a beefed-up character, presented in the well-muscled form of William Fournier, who struts his stuff bare-chested (brrrr!) as a fully-fledged member of the forces marshalled against Macbeth.

Simple staging and the very minimum of props focus attention firmly on the performances, none of which is less than competent. Colin Burnie’s Banquo and Bob Mann’s Duncan are much more than this.

One hopes that rather more in the way of malice can be added to Sam Knipe’s portrait of Lady Macbeth. At present, she reveals a rather too cheery persona. Dismissing the the guests at the end of the disastrous banquet — and here I feel, incidentally, that the non-appearance of Banquo’s ghost is a confusing mistake — she is like a kindly pub landlady clearing the place at closing time.

Continues until July 22. Tickets: 01865 305305 (www.ticketsoxford.com).