Peter Capaldi will miss the "many more smiles" he gets for being Doctor Who when he leaves the role at the end of 2017.

Peter Capaldi as the Twelfth Doctor

Peter Capaldi as the Twelfth Doctor

The 58-year-old actor has portrayed the Time Lord in the BBC sci-fi drama for almost four years but will exit the TARDIS for the last time in the 2017 Christmas Special.

Capaldi admits he will be very "sad" to no longer play the Twelfth Doctor as one of the things he has enjoyed most about landing his dream role is that children see him as the heroic character when he's out in public.

Speaking at a Q&A in London, he said: "I'm very sad to leave, apart from the fact it's a wonderful job we have this fantastic team of people in Cardiff who work incredibly hard. The crew are incredibly kind, hardworking and lovely to be around so that will be sad to not work with them. It will be sad to not be Doctor Who anymore because that's an incredible thing to wake up in the morning and say, 'Oh I'm still Doctor Who!' And then you go and blow up some monsters and that's how you spend your day. Also when you walk around people don't see people anymore, he's not here, it's Doctor Who they see and he gets many more smiles than I do."

However, Capaldi, 58, was reassured by showrunner Steven Moffat - who is also departing his job on the programme this year - that he will always be the Doctor to fans.

The 55-year-old writer-and-producer said: "To be fair, you will always be Doctor Who, you will retain the title forever, ask your predecessors they all think they're the real one. Peter Davison and David Tennant are still eyeing each other now!"

Looking to his replacement, Capaldi admitted he isn't fussed whether the new Doctor will be a man or the first woman to portray the character they just have to be "right for the part".

He mused: "I'm sure whoever that person is will be wonderful. Doctor Who is a wonderful part and if they haven't already done so they're going to make a wonderful choice by accepting it, whether that's a man or a woman is irrespective just as long as they are right for the part, that's the important thing."

Before he departs Capaldi will be seen on-screen with new companion Bill Potts (Pearl Mackie) and will get the chance to battle his own personal favourite classic monster - the Mondasian Cybermen.

The villains are the original version of the familiar cyborg foes, hailing from Earth's twin planet Mondas and they have not been seen in the show for over 50 years. They first appeared in 1966 serial 'The Tenth Planet' in what was First Doctor William Hartnell's final storyline before he regenerated into Second Doctor Patrick Troughton.

'Doctor Who' returns to BBC One on Saturday April 15 at 7.20pm with 'The Pilot'.