Finally available from networkdvd is the box set of this series. The very first 13 episodes were shot on film and they look great. The rest of the series was shot on video tape due to a strike at that time. It is impossible to make them look as good as the filmed episodes. Nevertheless this is a great series. Michael Quinn stars as Nick Craig in the first season as the lonely Ghost Squad agent. In the second season he is joined by Neil Hallett as Miller , and thereafter they used to share rotating episodes. The series was a groundbreaker and most of it stands well today. The whistling theme is as wonderfully evocative today as it was in 1961! Each week features one of the agents investigating murder, espionage and robbery.Quinn's character is a master of disguise and this leads to some entertaing episodes.Shot in dark corners and low key lighting the series ( especially the first season looks great ) The 3 rd series was entitled G.S.5 and Nick Craig did not return, his character had been killed off. I don't know if Quinn quit or was pushed , but without him the series died very quickly. If you love old 60's tv then the series is a must for you to collect.