Whisper it quietly lest we break the spell, but this week’s Merlin was the best yet. Once again it drove a coach and horses through the accepted legend, in this case by having the captive dragon forge Excalibur from an original made by Blacksmith Tom (although thankfully the “new imagining” retained the traditional words on either side of Excalibur’s blade), but the more irritating plot elements of previous week’s were attenuated while the better ones were accentuated. And we learned something new about Arthur.

Reanimated with a spell from Nimueh, the Black Knight crashed into Arthur’s investiture ceremony (spoiling a rather nice stained glass window in the process) and cast down his gauntlet in a challenge to the death.

In the manner of those red-shirted security guards from Star Trek: TOS who you’d never seen before and knew that you wouldn’t be seeing for very long, Sir Owain stepped forward to take up the challenge. He was, coincidentally, also wearing a red tabard although as that’s the livery of a knight of Camelot, this didn’t necessarily mean anything. He was still doomed though. For no mortal blade can kill that which is already dead. Apparently.

That didn’t stop Sir Pellinor having a go though. Never seen him before this week either, so that was a clue about how successful his efforts would be. As in, not very. Even though his blade ran the mysterious knight through too. Must be frustrating that, when you’re a knight.

Arthur’s frustration had certainly reached boiling point. He didn’t even wait for the next challenge, but impetuously threw his own gauntlet down first. Which was a worry for his old Dad, especially when Nimueh paid him a visit to reveal who the Black Knight had really come for, and why. Naturally Arthur was all knight’s code and honour, whereas Uther, being a bit of a dick (sorry, concerned father), wanted him to wriggle out of it.

Meanwhile Gaius and Merlin were desperately searching for a magical solution to the magical problem. Luckily for them Geoffrey of Monmouth had the scrolls. Which back in those days you couldn’t get any cream for. So that leads us to the aforementioned forging of Excalibur. Not in the sense of actual forgery, although thinking about it…

The dragon insisted the sword must only be wielded by Arthur, which made it an odds-on certainty that he wouldn’t. Instead Uther had Gaius knock him out with narcotics, happened to spot the sword (which wasn’t difficult as it was the only shiny one in the entire armoury, not to mention being the only one wrapped in red velvet), and despatched old BK with a nonchalant flick of his kingly sword arm.

So that was that. Except the dragon was a bit peeved that Uther had used his sword, and flew off shouting about dark consequences. Which meant Merlin had no choice but to cast Excalibur into the lake, from where it will presumably reappear in a later episode in the way it should have come into Arthur’s possession all along.

It may be happening at a glacial pace, but the threads of this series are oh-so-gradually being pulled together and beginning to hint that the final episode might repay the time we’ve invested watching the rest with a corker of a showdown between Uther, Arthur, Merlin and Nimueh. Which hopefully will allow Merlin finally to use some magic for something more significant than lighting torches and moving things about a bit.