It was Holiday 86 - a fab sig tune and only used for one series due to a new producer taking over for Holiday 87 and revamping the programme: http://www.youtube.com/watch?v=iL0B6VVUcBo
I quite like some of the themes from the BBC Radiophonic Workshop... Paddy Kingsland and Roger Limb spring to mind.
There can be only one :Edwin Astley
Gideon's Way
Department S
Danger Man
Randall & Hopkirk (Deceased)
The Baron
(but not the Champions as many seem to think, that was Tony Hatch).
The black and white Saint is pure Edwin Astley. For the colour episodes he had to include the bars composed by Leslie Charteris which turn up again in Return of the Saint and the Simon Dutton Saint. Charteris wrote them I think for the old films of the Saint.