THE DAY OF THE DOCTOR is everything a 50th anniversary celebration of DOCTOR WHO disserves to be. It not only works as a glowing and affectionate tribute to half a century of an icon of science-fiction, but it’s also a cracking episode in its own right, with an intelligent and mature script, and the scale and budget that the regular show so often lacks to make it worthwhile seeing it on the biggest screen possible.

As set up in the mini episode THE NIGHT OF THE DOCTOR (which finally gave Paul McGann the send-off he deserved), at death’s door the Eighth Doctor was allowed to choose the form of his next regeneration to help him fight in the Time War. The form he chose was a warrior, a War Doctor (John Hurt) who is seeking to end the war once and for all, even if it involves the genocide of the two species in conflict, the Time Lords and the Daleks. Meanwhile, the Eleventh Doctor (Matt Smith) and Clara (Jenna Coleman) receive a suspicious call from old allies UNIT, and in the Sixteenth Century, the Tenth Doctor (David Tennant) is having a fling with Queen Elizabeth I (Joanna Page) and on the hunt for shape-shifting Zygons. These three seemingly disparate plot strands converge into an epic wider story that pretty much changes Doctor Who lore forever.

One of the things I liked most about the special, in fact the main thing that gave it so much charm, was that it didn’t take itself too seriously. Yes, there’s half a century of sci-fi mythology to draw on and pay tribute to, but Mofatt and the cast don’t shy away from poking gentle fun at some of the series’ well-known concepts and character traits. The best scenes by quite a way involve the three iterations of The Doctor as played by Smith, Tennant and Hurt squabbling and making fun of each other. Who else could play a grizzled, conflicted and exhausted iteration of The Doctor better than Hurt? He makes a brilliant contrast to the frivolous and energetic Smith and Tennant, and brings real acting heft to the episode.

The episode (or TV movie, however you view it) also appears to be pretty aware of how Doctor Who is regarded by fans and non-fans alike. Several references are made by Hurt’s Doctor to the childish personalities of Smith’s and Tennant’s, to their unwillingness to act like “grown-ups” and I’ve always seen that as one of the main appeals of the show to Whovians. Ideally, you’ll start watching it as a child, and if it makes enough of an impression on you then it’ll be with you for the rest of your life. For many, the show always remains a reliably fun piece of escapism to return to when real life is getting you down.

But grown-up is just what The Day of the Doctor is. You don’t tend to see much nuance in Doctor Who scripts, and though the underlying themes are often grand, they’re rarely this complex. It’s all wonderfully reflected in the emotional state of the three Doctors. Hurt’s character is at the precipice of a complete moral downfall. A good man is on the verge of going bad, even if his despicable decision is made for the right reasons, for the greater good. He’s seen horrors, but none on the scale of what he is contemplating doing himself. Tennant’s Doctor has already made that choice, and is still crippled by guilt. Smith’s Doctor has had to live with his decision for centuries, and has buried his regrets so far within himself that they could have happened to someone else entirely (and in The Doctor’s case, you could say that they did). Beneath the shinier-than-usual special effects and multi-Doctor banter, Steven Moffat has produced an intelligent exploration of morality and mortality, and an episode that progresses the main story nicely, with numerous interesting implications for the future.

Being a anniversary episode, it is of course expected to pay homage to what has come before. Every Doctor gets to take a short bow in a spectacular finale, and you can look forward to one very special cameo before the credits roll. As well as tying up loose plot threads both from the classic and revived series, there’s also a good number of in-jokes for fans to spot.

All in all, The Day of the Doctor is a rousing success. If not for THE EMPTY CHILD, it would be the best thing Steven Moffat has ever written. The timey-wimey stuff is tightly plotted and mostly makes sense (not always the series’ strongpoint), the character motivations are focussed, and the script is satisfyingly meaty. I really can’t think of a better way to cap off fifty years of a British cultural institution.

It’ll be sad to see Matt Smith go at Christmas (not quite as sad as I was about Tennant’s departure, but still). It’s not like it’ll be the last we’ll see of the Eleventh Doctor. Doctor Who has a long history of reunions, so I’m sure Smith will slip on the bow tie again sooner rather than later. Apart from that, bring on Peter Capaldi! SSP