Shaun Evans is back as a young Inspector Morse in the seventh series of ITV hit Endeavour. The actor, who also directed the first episode, talks to Georgia Humphreys about the importance of challenging himself.

Since it first hit our screens in 2013, detective show Endeavour has become hugely popular.

Which is no surprise really, considering it's a prequel to Inspector Morse - the beloved ITV crime series starring the late John Thaw as the titular character.

Now in its seventh series, Endeavour sees Shaun Evans play a young Morse - who first appeared in novels by British author Colin Dexter - alongside Roger Allam as DCI Fred Thursday.

In the first episode, it's New Year's Eve 1969. Normal order has been resumed and the team are back together at Castle Gate CID.

However, the events of the past year have left their mark, and we can expect old friendships to be challenged, while new relationships blossom.

Here, Liverpudlian Evans, 39, tells us more.

HOW WOULD YOU SUM UP SERIES SEVEN OF ENDEAVOUR?

This is the shortest one we've done - there's only three films this time. There's way more connective tissue between them, so while you can watch them all individually, you can see them as a three, as a proper series.

The main thrust of the story, it's less 'story of the week' and more an ongoing narrative, which is the nucleus of the separation between myself and Thursday.

ENDEAVOUR IS A VERY ENIGMATIC CHARACTER, ISN'T HE?

I think that's a good thing, though. It's a fallacy that we know everything about someone. That's why it always makes me laugh when actors say, 'I know everything about this character' - I just don't see that.

I still surprise myself some of the things I do. I think, 'What were you thinking?' And your work as an actor should be the same. There should be a degree of holding something back.

YOU RECENTLY RE-READ THE BOOKS THE SHOW IS BASED ON. WHAT DID YOU TAKE FROM THAT?

The characterisation in the books is terrific. You have way more liberties with books than you do with a screenplay or with film or TV series, so how you plot the clues can be done in a way that you can't in the visual medium.

There's something about that cryptic mind, which is into solving crossword puzzles but, likewise, seeing the clues to a murder and it being the same part of the brain. It was that that I was thinking about going into it again this time.

ENDEAVOUR HASN'T BEEN VERY LUCKY IN LOVE. WE WERE HOPING THIS SERIES HE MIGHT GET A BREAK...

But where would be the fun in that? I think what's great about Violetta [played by Stephanie Leonidas] in this series... She's a character we haven't seen before in Endeavour, someone who's completely unobtainable and the 'other', in as much as she's quite wealthy and flies around the world seemingly, and is incredibly enigmatic on the one hand, but then is very available on the other hand.

By the end of this series, my hope is that she occupies a very distinct and unique place in the history of this character, which makes him the person that he becomes. She's a very definite stepping stone on the way to that.

HOW HAS YOUR PREPARATION CHANGED FROM WHEN YOU FIRST TOOK ON THE ROLE?

Well, you don't want to be complacent as an actor. This is an amazing job in many ways, but there's also a danger that you become lazy with your work. So I've always tried to push myself, to be producing or to be directing and to be doing things alongside and in conjunction with this. Part of that is not making it too easy for yourself, so you're not just playing yourself.

That's why it was important, for me personally, to read the books again, and be like, 'I'd forgotten that' or 'I missed that' or 'That's interesting'.

You've got to stay engaged in it, otherwise I won't get anything out of it myself, and then the whole job would have been a waste, is the way I see it.

YOU DIRECTED THE FIRST FILM OF THIS SERIES. IS IT DIFFICULT DIRECTING YOURSELF?

Yeah, that can be a challenge. But I like a challenge, first and foremost. And it's interesting, because my opinion of acting and characterisation within a story has changed because of having an overview as a director.

It's challenging from a time-wise point of view. But, if you prepare and you've got a good team, then you can achieve anything.

Directors can come in and they have an overview of the story, but I've been in it for a long time and so that brings with it a fresh perspective. At this stage, I think that's a good thing.

IT'S A LONG-RUNNING SHOW WITH A STRONG VISUAL IDENTITY. HOW DO YOU PUT YOUR OWN SPIN ON IT?

Each director brings their own DP [Director of Photography]. They have their own unique story, so they bring their own cast as well, and they are encouraged to make it as much about them as is possible. So, the stories can have a similarity, but there is - hopefully - no house style with this show.

When I watch it back, I can always see the director's personality in it, just by the things that they laugh at, the things that they're interested in story-wise, the plot, things that are important to them or not, and how that relates to a visual language.

Endeavour returns to STV, tomorrow, 9pm