Howling:Torchwood, UNIT and the Doctor

A few continuity questions raised by the retroactive addition of Torchwood into the Doctor Who.

If Torchwood (London and Scotland at least) were sworn enemies of the Doctor why didn't they take advantage of his being grounded on Earth during the Pertwee years to intercept him? Was Lethbridge-Stewart protecting the Doctor somehow or did they somehow not realize the UNIT Scientific Advisor Dr. John Smith was actually *the* Doctor?

A related question - if Jack was stranded on Earth for over a century waiting for the Doctor why didn't he pay a visit to the Third Doctor when he was at UNIT?