[1] The series recounts the adventures of a gang of street urchins living in Victorian London who assist the legendary detective Sherlock Holmes in solving crimes and find themselves tackling cases of their own.
[1] Although Holmes was always absent (explained on-screen by his being too busy working on another case, being held captive by Professor Moriarty, or confined to bed by illness), Dr. Watson was always around to assist the Irregulars when necessary.
Holmes was only ever seen obliquely[1] (Roger Ostime provided the character's voice) while Dr. Watson, Inspector Lestrade and Mrs. Hudson all featured more prominently.
[1] A year prior to playing Watson in this series, Hubert Rees has briefly appeared as Inspector Lestrade in a 1982 adaptation of The Hound of the Baskervilles.
The part of Professor Moriarty was portrayed by Colin Jeavons, who would later go on to play Inspector Lestrade in the acclaimed Granada Television adaptation.