Does anyone watch Spooks? See this.

[booksforsale]

http://www.youtube.com/watch?v=bOJBfglPmio&NR=1

Who is that groovy guy 51 seconds in?

[kengillam]

To blurry to see.

[damian_steele]

http://www.youtube.com/watch?v=bOJBfglPmio&NR=1

Who is that groovy guy 51 seconds in?

He's the guy who plays Harry Pearce - the boss man.
His name, as it clearly says in the titles, is Peter Firth.

[booksforsale]

Here is a clearer view of a young Peter Firth.

A full episode in two parts

Part 1

Part 2

If a full episode of Here Come the Double Deckers is too much for you, just watch part two to see a clearer picture of a young 'Harry Pierce' straight away. I do recommend watching the lot if you cherish 1970s kid's TV.