Imagine, if you will, sitting down on a Thursday evening to watch a satirical comedy show, a show that portrays someone who was at one time the most famous woman on the planet as a ditzy, blonde singleton, bumbling her way through conversations and getting into all sorts of trouble. Diana could so nearly have been this show were it not for the dull love story sandwiched in between the often bizarre, wooden dialogue.

The film begins in Paris, 1997, with a scene that foreshadows her inevitable fate. We then see events from the final two years of her life play out with the narrative focusing on her relationship with heart surgeon Hasnat Khan (Naveen Andrews). Very little of the relationship is officially documented, leaving a huge number of blanks for the filmmakers to fill in, a task which they attempt with gusto. Diana (Naomi Watts) drives around London in a brown wig and a beaten-up car, on her way to secret liaisons in Soho jazz clubs. The relationship comes under fire when Khan struggles to reconcile a life in the spotlight with his life as a doctor and with his family in Pakistan. The more famous of Diana’s post-Charles affairs, her relationship with Dodi Fayed, is relegated here to a rebound fling, cooked up by Diana to get back at Khan. It’s the closest this film comes to a conspiracy theory, but by this point, audiences will be too bored to care whether what they’re watching is real or a fabrication.

It’s something of a surprise too, given the fact there are few roles that scream “Oscar bait” louder than Naomi Watts as Diana, and direction is handled by Oliver Hirschbiegel who was responsible for one of this century’s greatest historical biopics in Downfall. Under different circumstances, this pairing could have resulted in something fascinating. Alas, we will never know what could have been, because the two are forced to contend with writer Stephen Jeffreys’ utterly insipid script. Most of this film’s awards next March will probably come from a few miles down the road at the Razzies ceremony.

Diana’s plot is rarely interesting and the problems faced are far too simplistic. Khan constantly complains that he couldn’t marry Diana and remain a doctor, but never actually explains why, and the film sluggishly rolls on, barely resolving itself before the inevitable finish. Watts and Andrews fail to eek even an ounce of chemistry from a terrible script, awkwardly stumbling from line to line of clunky dialogue. At times, the screenplay feels like it was written by a computer that has spent a year watching daytime TV dramas, analysing the scripts and coming out with what it believes to be natural human speech. Some lines in Diana come so far out of left field as to leave one questioning whether they actually heard correctly. In a satirical comedy, there are moments here that would be praised for their bizarre, eccentric wit, in Diana however, they come across as embarrassingly misjudged.

A good film could have been made about Diana’s life after Charles, the subject matter isn’t the problem here. The problem is an abysmally bad script that, while occasionally hilarious, doesn’t offer enough ‘so bad it’s good’ moments to make it worth trudging through. Rather than being the off the wall BBC comedy that it occasionally feels like, Diana is a daytime TV drama not even worthy of Channel 5, but rather one of those channels you didn’t even know existed until you pressed the wrong button on the remote. And there, hopefully, it will stay buried and forgotten about, only resurfacing briefly to clean up at next year’s Golden Raspberry awards.