Alastair Mackenzie is reuniting with his Monarch of the Glen co-star Dawn Steele in season 3 of Granite Harbour20:17, 23 Jul 2026BBC's Granite Harbour is returning for season three with some new cast members.‌The Scottish detective drama will see Alastair Mackenzie join the cast list alongside fellow newcomers John Gordon Sinclair, Ellie Haddington and Ryan Fletcher. They will star alongside returning actors Dawn Steele as DCI Cora Macmillan, Romario Simpson as DC Davis Lindo, and Hannah Donaldson as DS Lara 'Bart' Bartlett.‌Alastair Mackenzie will star as Richard Loughty, a charming and well-respected landowner who seems to be very charitable to all and sundry, especially to the local traveller community who live on his land. However, cracks begin to appear in his charming veneer when sketchy things start happening on his estate.‌Alastair's new gig on Granite Harbour will see him reunite on-screen with his Monarch of the Glen co-star Dawn Steele for the very first time.Speaking about working with her again, Alastair said: "We are very good pals and it was an utter joy to be on set with her again, although we did not have many scenes together. It was very nostalgic too.‌"Monarch was a very happy time and so well-loved by so many people and Dawn was so fabulous as Lexie. She’s a national treasure really. It was lovely but we always giggle a lot, so we had tried hard to be very professional! I think it worked."Alastair rose to fame on the BBC comedy drama that launched in 2000 and ran for five years. The heart-warming drama was based on Compton Mackenzie's novels and featured a rural community of eccentric characters.Alastair played Archie MacDonald on the show, who became the laird of a huge, decaying family estate in the Cairngorms. Alastair had roles before Archie, including playing Dr. 'Shug' Nevin in the television series Psychos, and has had plenty of roles since.‌Characters that stand out include Jeremy Welsh in Borgen, Lord Rothcroft in Dracula, William Brereton in Wolf Hall, Craig Petrie in The Loch and Jamie in Cold Feet.He is also known for playing Guy Riverty in Deep Water, John Bentley in ITV's hit drama Unforgotten, Simon Lanesborough in Professor T, Richard Aylard in The Crown and Perrin Fertha in Andor.‌As well as his extensive list of television credits, Alastair has regularly appeared in theatre and on film, as well as directing and producing. His brother is director David Mackenzie, with whom he co-founded Sigma Films.But they are not the only talented members in the family, as Alastair is married to fellow actor Susan Vidler. The couple share two children.Susan starred as DSU Alison Powell in the BBC hit drama Line of Duty, Isobel Tulloch in Shetland, Aunt Sharon in Doctor Who, and Donna Brunos in The Jump.‌Film credits include Trainspotting, where she played Allison, Naked and Stella.The couple both hail from Scotland, with Alastair speaking out about the importance of art made and filmed there.‌He said: "I love being in Scotland. That’s where my heart is. I was able to fit this [Granite Harbour] in around filming a series of Blood of my Blood nearby and they both meant that I was in Scotland for quite a while last year."The Scottish film and TV industry is thriving and I’m proud to have played a small part in that. Scotland is home to not only the most amazing locations but also the most amazing technicians and actors. It’s actually pretty hard to get things made in Scotland at the moment because there’s so much going on and everyone is booked up. What a good problem to have. I hope to be working back there just as soon as I can."On what attracted him to the role of Richard on Granite Harbour, Alastair shared: "I enjoy playing characters with some mystery and perhaps even some darkness to them. Humans are complex and it’s all too easy to judge a book by its cover. Also, this was one of those jobs where I knew it would be fun and I relished the chance to be back in the Motherland."Article continues belowGranite Harbour series 3 launches on BBC Scotland on Thursday, July 23 at 9pm, followed by BBC One on Friday, July 24 at 8pm. All episodes will be available to stream on BBC iPlayer from July 23.