All though the whole cast agrees that they will be very sad it will be ending, they understand Johnny and Julian’s decision to end it on the series high.

Bradley James mentioned it earlier already in an interview that the series should end at it’s strongest point, according to the cast this season is definitely it’s strongest so far and a good moment to end the series.

Merlin Season 5, Episode 1 - 'Merlin's Bane - Part 1'. Merlin (Colin Morgan)

Colin Morgan: “The show has grown and grown each year and now we’ve arrived at its strongest point and we’ve achieved what we set out to do… I know this is the end, and I know this is goodbye, but thank you for being there on the journey with us because it has been a lot of fun!”

Merlin S05E03 - 'The Death Song of Uther Pendragon': King Uther

Anthony Head: “As for myself, I really miss working with such a talented and warm-hearted bunch of people – cast, crew, production. Everyone in London, Wales and France made the Merlin experience a very, very special one. Thank you all.”

Merlin Season 5, Episode 1 - 'Merlin's Bane - Part 1'. King Arthur Pendragon (Bradley James)

Bradley James: “My words won’t do justice to the honour of being King Arthur, so I shall just say that it has been an exceptional one, and that knowing the show has been a part of so many people’s lives has been humbling.”

Merlin S05E06 - 'The Dark Tower': Morgana (KATIE McGRATH)

Katie McGrath: “The breathtaking finale of this series leaves you with no doubt that characters have been on their journeys and had their stories told – it’s completely the right time to draw our telling of the story to a close.”

Merlin S05E02 - 'Arthur's Bane - Part 2': Gwen (Angel Coulby) and Sefa (Sophie Rundle)

Angel Coulby: “I think we’ve told the story we set out to tell, which ends with the fantastic two-part finale, by the way! I believe the key to any successful show is making sure you leave people wanting more!”

Merlin S05E04 - 'Another's Sorrow': Gaius (RICHARD WILSON ), Princess Mithian (JANET MONTGOMERY)

Richard Wilson: “Speaking as Gaius, I feel I have mentored the young wizard as far as I can – he is much smarter and greater than me now and I am simply exhausted!”

Read more: http://www.digitalspy.co.uk/tv/s53/merlin/news/a440706/merlin-final-series-colin-morgan-anthony-head-on-show-end.html