Mr Castles, who started life in the North Street area and is a former pupil of Lurgan College, was one of the first voices heard on air when Downtown started in 1976, hosting a Saturday afternoon sport’s show. The 67-year-old was also well known for his hugely popular phone in show on a Sunday morning.
Harry passed away after a short illness in Spain, where he’d been living with his wife since retiring in 2006.
Downtown Radio passed on condolences to his wife Liz, his two children Darren and Julie and the wider circle of family and friends.
Downtown/Cool FM Managing Director David Sloan paid this tribute: “A lot of journalists out there started off with Harry and got advice from him.
Apprentice Boys of Derry: new era of respect makes for enjoyable ‘Relief’ parade
Thousands expected to take part in 'Derry Day' this weekend
Feile organisers asked if they have warned Wolfe Tones about leading young people in pro-IRA chants
Brexit: There’s a fundamental con trick being played over Liz Truss’ Northern Ireland Protocol Bill says Lord Empey
DUP MP calls for probe into Sinn Fein MP’s Twitter post
“When he retired from Downtown he went off to Spain - he got a few good years but then his health started to fail and unfortunately in the last couple of weeks he deteriorated quite quickly and sadly he passed away in the early hours of this morning.”
David added: “Journalism is a serious business but Harry would always see the funny side of it and there was always a joke to be told, or a mishap, or something that went wrong.
“He was a really good broadcaster. With his easy, relaxed style of broadcasting he made everyone feel as if they were listening to a friend.”