The sun pipe is the modern version of the skylight. It's basically a tube with a mirrored inside surface. You poke one end through the roof and the other end through a ceiling. The ceiling end has a diffuser on it. As the tube is flexible, you can now bring daylight into an area that has no direct access to the sun.
But the sun pipe people need to think big. We really need one over London. Something a couple of miles wide, moored to (say) the Gherkin, would provide guaranteed, full-spectrum daylight to the City, Docklands and much of the West End. It would of course need to be quite a tall pipe, in order to break through the cloud cover.
I'm not entirely sure what effect the Grand Metropolitan Sun Pipe would have on local weather conditions. I imagine that clouds cosying up to the exterior surface of the pipe might well turn to moisture, creating a near-constant run-off down the structure. This valuable resource could be harvested at the base, or even bottled and sold to gullible tourists.
Is this the great engineering project we're looking for, now that the Channel Tunnel is such a rip-snorting success, our high-speed trains thread the countryside and our new generation of NHS IT systems is revolutionising healthcare? Yes! Obviously.