BBC Two's An Adventure in Space and Time - commissioned to mark Doctor Who's 50th anniversary - is a lovingly crafted piece of work. Gatiss has spoken on several occasions about how this 'origins' drama has been a long-held passion project and that passion has filtered through to every element of the production.
There's so much to admire, from Edmund Butt's brilliant score to Dave Arrowsmith's gorgeous production design, with its pinpoint accurate reproductions of costumes, the TARDIS exterior and, best of all, the control room - perfect in every detail, right down to the green hue of the console.
The chief reason why An Adventure is so successful though is ultimately Gatiss's script. If you're a Doctor Who buff, you'll find countless knowing nods to the show's history and mythology contained within these 90 minutes.
But it also works as a standalone piece of drama, one that can be enjoyed by any Who novice out there. You might appreciate what's unfolding on screen on a slightly deeper level if you're a fan, but it's certainly not a requirement.
That's because as much as An Adventure is about the creation of Doctor Who, it's also about the changing role of women and minorities within the television industry in the 1960s, and it's about one man's incredibly moving Christmas Carol-esque journey from miser to children's hero.
You don't need to be a hardcore Whovian to be moved by what is in essence a story of discovery, redemption and loss - and make no mistake, An Adventure in Space and Time is a hugely emotional piece of work.
It threatens to bring a tear to your eye almost immediately, as a sickly Hartnell is told that he needs to "move along" because he's "in the way" - an unwitting policeman unaware of the weight behind his words. But the biggest gut-punch is reserved for the drama's final moments.
Having Matt Smith appear in An Adventure in Space and Time could've come off as gimmicky - a cheap attempt to link this project to contemporary Doctor Who for those unfamiliar with the show's '60s origins.
It's not that at all though - the moment in which Smith and Bradley exchange a glance, each so proud of the other, is as affecting as television drama gets. There's so much meaning - so much history - in that one shared moment between these two men. It's Mark Gatiss's final humble bow to William Hartnell and it's beautiful.
Bringing Gatiss's heartfelt script to life is a strong roster of actors - Andy Pryor is another name deserving credit for his spot-on casting. Acting legend Brian Cox is great fun as flamboyant Sydney Newman, Sacha Dhawan brings a fresh-faced likability to the role of director Waris Hussein, while Call the Midwife's Jessica Raine is wonderful as the spirited-yet-vulnerable Verity Lambert.
Then there's David Bradley, perfectly capturing the mixture of hard-headedness and compassion that made the first Doctor such a memorable character. Though, with that said, it's perhaps the portrayal of Hartnell that could potentially be a sticking point for some.
Here, the actor resembles the popular image of the first Doctor - crotchety and irritable, but with a good heart. Gatiss didn't want this to be a "hatchet job" and in this anniversary year, it's only natural to want to give any Doctor Who-related programming a celebratory slant.
But the darker elements of Hartnell's personality are somewhat glossed over and the closest we come to one of his famed on-set altercations is a brief scene in which he brusquely tells co-star Carole Ann Ford (Claudia Grant) that she shouldn't spend her cash so quickly.
Did Hartnell really go on quite such an obvious emotional journey - from snapping at his granddaughter to larking about with kiddies in a park? Was his bad behaviour really just the result of an unquenchable feeling of loneliness, amplified by Doctor Who's endless stream of cast and crew changes?
You could easily pick at the veracity of the script, but to do so would be rather missing the point of what Mark Gatiss was setting out to achieve. An Adventure in Space and Time isn't meant to be taken as a historical document.
Gatiss wanted to make a human drama that was entertaining and uplifting - and on that level, An Adventure in Space and Time is pretty much perfect.