The classic series of Doctor Who didn't really deal with series finales. Bar maybe The Key To Time, the last serial of a classic series season would instead tend to be a standalone adventure, wrapping up its own individual plot rather than an entire over-arching narrative. It's a style that proved to work well time and time again for the classic series, and so it's no surprise that they largely maintained this approach.

'The Ultimate Foe' is a different beast. It follows the line of thinking we have seen more with the new series, acting as a conclusion to the Trial Of A Time Lord arc rather than just another Doctor Who adventure. It's an approach that works significantly well for it, as it plays more with the format of the courtroom proceedings, finally giving us witnesses from the Doctor's previous stories this season. We get o see Glitz (Tony Selby) again, and we're reunited with Mel (Bonnie Langford). It's a really effective way to establish these past stories in further with the 'Trial' storyline, as they become an integral part in solving the Doctor's conflict with the Valeyard (Michael Jayston).

The Mysterious Planet in particular is revealed to have a very strong link to the events of the courtroom trial, as we learn the reason why Earth was renamed 'Ravalox', and discover that the High Council of Time Lords were behind the solar flares that almost destroyed the planet. This leads to arguably Colin Baker's greatest performance in the classic series, as he scolds his own species for their part to play in the disaster that befell the Earth. The writing by Robert Holmes and Eric Saward here is so beautiful that feels like pure poetry, as the Doctor declares that Daleks, Cybermen and the other monsters he has encountered are 'still in the nursery' compared to them. It's undoubtedly the strongest the writing had ever been during Colin Baker's era, and it's a crying shame that the rest of his time in the TARDIS hadn't featured writing quite as magnificent as this.

This serial also sees the return of Anthony Ainley's Master, and he's on excellent form here. Whether it's on the video screen in the courtroom or aiding the Doctor and Glitz in the Matrix, he brings exactly the same huge amount of screen presence as you would expect from this incarnation of the Doctor's Time Lord nemesis. The best thing about his appearance here however is how it subverts expectations. Naturally as a viewer you expect him to be the man behind the manipulation of the Matrix, and the one trying to get the Doctor sent down for genocide, but for once the Master isn't out to get the Doctor. He takes up more of an ally role here, assisting the Doctor in trying to take down the Valeyard, the real culprit behind the corruption of the Matrix. I'm glad the story refrained from going down the obvious route, as it allows for a new central conflict to form.

Many have spoken about just how brilliant of an idea the Valeyard is, an amalgamation of the Doctor who comes somewhere between his twelfth and final incarnation. He makes for this really intriguing premise, as his origins, where he comes from and how he was formed is kept so deliberately vague. Thirty five years, and we're all still hooked trying to figure out more about this enigmatic figure, and when he will next appear in the series. That right there is a clear cut sign of good writing. If a piece of TV is so talked about and discussed many years later, then quite clearly it has done something right, and it's a crime that the Valeyard is yet to return on TV.

The majority of the Valeyard's scenes take place within the Matrix, and these scenes demonstrate such a wild amount of creativity and imagination. Whether it's the Doctor being pulled into the sand, grabbed by a pair of hands as he peers into a barrel of water or encountering 'Mr Popplewick', who is obsessed with 'procedure', there are so many impressive sequences here that demonstrate the limitless scope and scale of a show like Doctor Who. It's almost like watching a David Lynch movie mixed with Alice In Wonderland, in the way that it embraces the weird whilst openly acknowledging that none of it makes sense. As the Doctor states, 'The only logic is that there's no logic'.

If there's any criticism I could level at this serial, it's that it short-changes both of the Doctor's companions. Firstly, we are told by the Inquisitor (Lynda Bellingham) that Peri actually survived the events of Mindwarp, and is living happily with King Yrcanos. Pushing aside the fact that it's detrimental to the huge emotional impact of Peri's emotional exit, it's disappointing that we don't actually get to see Nicola Bryant and Brian Blessed here, especially when they could have just filmed it quickly at the same time as Mindwarp. Secondly, Bonnie Langford as Mel is not given a great deal to do. She's largely relegated to the trial scenes, although she does get to enter the Matrix later in order to inform the Doctor that his 'guilty' verdict was a Matrix illusion conjured by the Valeyard. It would have been nice if Mel had contributed more substantially to the plot, as even with the information she passes on to the Doctor, his reply is that he already knew it was fake anyway.

Overall, 'The Ultimate Foe' is an extremely underrated Doctor Who story within the Whovian fandom. It's a serial that not only gives us Colin Baker's greatest performance as the Doctor, but also provides a wildly imaginative narrative concerning the illusions of the Matrix, delivers some truly intriguing details regarding the Valeyard and offers another stunning return for Anthony Ainley's Master. This serial is easily the greatest of the classic series' two part adventures, and a prime example that two part 'Classic Who' stories can totally work.