This is about 40 years too late, but there's now an official Progressive Albums Chart Top 30 in the UK. The Official Charts Company, which is a partnership between the British Phonograph Industry association and the Entertainment Retailers Association, is the official keeper of all the British music charts, and it's just gotten around to launching this new chart now.
While you'd expect pro-rock stalwarts like Roger Waters and Pink Floyd to have slots, it's surprising the number of 21st Century acts that make up the top 10, with Tame Impala taking the top spot.
Here's the first version of the chart.
Official Progressive Albums Chart - Top 10