I've been travelling in Australia, Brunei and Singapore for the past three weeks, and came back with a heavy cold. Fortunately, my sister had saved the Listener 4406, 4407 and 4408 puzzles for me, so I had something to do while recovering.
Listener 4409 was very enjoyable. I actually did quadrant C first, then quadrants A and B more or less in parallel, which gave enough information to search for the long quotation. Quadrant D was by this stage a relative "walk in the park".
One query: I note that all the thematic answers are to down clues. This makes sense in quadrants B and D, given the necessary treatments, but doesn't seem necessary in quadrants A and C. Have I missed something, or is this just a coincidence?