Yes Mark Slade played Blue Boy Cannon. It was on at 8pm on BBC2 on a Monday night and when the season ended Lancer was on instead. Victoria Cannon was the sister of Manilito Montoya played by Henry Darrow and John Cannon (played by Lief Erickson) and his brother Buck Cannon played by Cameron Mitchell ran the High Chapperal, my mum and dad went to see the High Chapparel just outside Tuscon Arizona in 1997 but apparently it had been burnt down.
Rudi Ramos played my favourite character 'Wind' in about season 3 when Mark Slade left the show.
That's about all I can remember, oh except the brother Sam and Joe who worked for the cannons were played by Bob Hoy and, errr, I've fogotten whoi played Sam now, he was in a few John Wayne movies.