This series was highly popular when first broadcast on ITV almost 40 years ago.The basic premise is that 3 undercover police officers are seconded from the Met(London Police) to an unnamed city in the North Of England where they are totally unknown to the local villains,hence the title.The trio are led by Det .Sgt Bulman played by Don Henderson whose trademarks are his perennial gloves ,nasal inhaler and plastic carrier bag.The stories aren't just the usual drug dealers,pimps and blaggers,but suspect councillors and people who get themselves involved in crime by their lack of common sense.
Dennis Blanche plays Bulman's action man sidekick and the trio is completed in the first two series by the excellent Frances Tomelty, who to be honest,never seemed totally happy with the role and was replaced in series 3 by Fiona Mollison who was a kind of Purdey like character,posh accent and well able to look after herself in a tight corner.
At times the stories can be very slow moving,making Inspector Morse look like Starsky and Hutch but the lack of shootouts and car chases adds to the worth of the show.
Available from Network DVD in the UK and currently very well priced for the complete series on Amazon UK.
Worth getting hold of if you're a fan of British cop shows from the period.
The series spawned a spin-off "Bulman".