For this image to really work the data set needs to be much larger, there are only ~44k points on this map, increasing the point radius would not work in the towns/cities as they are too close. In order to use a larger point radius than one pixel I would need to move down to the more detailed Ordnance Survey tiles.
Using the options panel on the left you can change some of the details around.
Contains Royal Mail data © Royal Mail copyright and database right 2012.
Contains National Statistics data © Crown copyright and database right 2012.