Is this breed of dog nearly extinct as I haven't seen one for 20 years, yet they were a common sight in the seventies?

Don't think so, there's loads around here. Maybe they are less popular inner city due to size and energy?

Theres a few around here .Each one of them as nutty as the next .

I met an English Setter once. Boy are Setters extreme players. He was like on sugar or something.

LOL, yep!
We looked after one for a few months when I was a teenager - It was mental.

Lovely looking dogs, but I agree with others, all completely mad.