I came across his work from that program when I first saw it a few years ago. In the course of the show, he paints quick oil sketches in the manner of several late-19th century painters. His own work is a little more toward interpretive semi-representational landscapes than I would have expected, but I very much like some of his compositions suggestive of reflections in water, and those in which he walks the line between abstraction and naturalism a bit closer to the representational side.
Dunlop’s website has a gallery of his paintings and links to a number of his projects, including Landscapes Through Time — which I believe is due for production of a second series — and a 4 DVD independent series, Painting Landscapes with David Dunlop, and another titled Painting Skies with David Dunlop.
I haven’t seen the latter two sets yet, but I assume they are similar in style to Landscapes Through Time, and you can probably get a feeling for them by viewing his YouTube videos on Ten Minute Oil Sketch, Fog Painting at Prouts Neck, ME and others.
Of particular interest is Dunlop’s blog, on which he engages in more of his thoughtful analysis of various aspects of painting, particularly as it relates to the 19th century painters with whom he feels an affinity.