Answer: They have all lived in Cookham, but nobody has erected a blue plaque to commemorate Timmy Mallet (yet).
Full screen map here
Our local authority publishes a list of blue plaques, but the locations they give are a bit woolly, so I've been getting a bit of exercise hunting them out and adding them to OSM over the last couple of evenings.
Thanks to Mappa Mercia for the idea. And for anyone considering a similar exercise, Open Plaques provide an extensive list of Blue Plaques here They use OSM as a base map, and extract geotagging from Flickr.