With a richer feel, thanks to a shift onto 35mm film, plus a slightly darker tone, it appears that Merlin has come of age.

The cast look noticeably more grown up and indeed even the opening narration now refers to the warlock as a ‘young man’. Supplying a better balance between the humorous and dramatic, Series 4 dispenses with the out and out comedy and provides a strong run of episodes that begin to deal with the major elements of Arthurian legend.

An impressive array of guest stars include Gemma Jones (Spooks), Phil Davis, Lindsay Duncan, James Callis (Battlestar Galactica), Gary Lewis (Billy Elliot), Janet Montgomery (Entourage), Miranda Raison (Spooks), Ben Daniels (Law & Order: UK) and the return of Santiago Cabrera (Heroes) as Lancelot.

In story terms, two characters find themselves swiftly forced to become more responsible for their actions. For Morgana, losing her half-sister Morgause and gaining a henchman puts her in a position of outsider and in the role of series recurring ‘big bad’.

With Arthur, the incapacitation and subsequent death of his father in The Wicked Day makes him King with all the attendant responsibilities. It is his journey of discovery, grappling with the realities of kingship, which really shapes the run.

With the Knights of Camelot now present in force, Percival, Elyan, Gwaine and Leon each get their own chance to shine, notably Elyan in the spooky A Herald of the New Age where a restless Druid spirit possesses him.

Episodes such as Aithusa and Lamia provide some Boy’s Own action for the gang, though sadly some of it seems to be at the expense of Gwen, who’s left with little to do in the early part of the series. Later this is remedied with Lancelot’s return from the dead, their tryst and her subsequent banishment providing action and heartbreak in equal measure.

Gaius too takes a back seat, though he too has an episode where his long running, unspoken distrust of the newcomer Agravaine comes to a head. As Morgana’s agent in Camelot, Arthur’s uncle provides untrustworthy advice to the young King throughout and Nathaniel Parker does will with some slim material at times. He also seems to be the inheritor of Katie McGrath’s evil smirks as she gets the chance to be the out and out bad girl, which she does with aplomb.

For Merlin himself it is another series behind the scenes, but that is not to say that Colin Morgan doesn’t have plenty to do.

From surreptitiously rescuing a dragon’s egg from destruction, to facing Morgana (albeit dressed as his aged alter-ego Emrys) and finally stage-managing Arthur’s pull of the sword from the stone, Merlin is becoming the master manipulator of legend.

The distrust between him and Agravaine across the series comes to a violent end in the series finale and where we see the lengths he will go to in order to protect his King.

> Read our review of the extras.

Released on DVD and Blu-ray on Monday 23rd January 2012 by Fremantle Home Entertainment.

> Buy the DVD boxset on Amazon.

Watch the Series 4 trailer…

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