This visualisation of London RAJAR data is based on charts created by Professor Hans Rosling at Gapminder.

The visualisation is built using Google's Motion Chart - they bought the technology from the Gapminder Foundation in 2007.

Note that because of the amount of data behind this chart, it may take a while to load up properly. It's being fed from a Google Doc. So be patient!

To use the chart, first hit the "Play" button in the bottom left-hand quarter. You can "scrub" the timeline going back and forth in time to see the changes more slowly.

This chart is a sister chart to the National version that I've been updating for a few quarters now.

As with the National version, there are a few things to note:

Otherwise have a play. My "default state" for the chart would be Average Age v % Male, with the size of the bubbles representing the stations' listening hours, however in the new improved version of Google's Motion Charts, I haven't worked out how to set this.

But there's plenty more data behind the scenes. Change the x-axis to "Hours" and see quite how dominant Capital was at the turn of the millennium when Chris Tarrant still reigned supreme in London radio. Have a look at how dominant Radio 4 is in average listening hours. See the constant battle amongst commercial stations to be number one in London.

There are a few different demographics to play with on this London version of the chart.

All the individual services are clickable. If you highlight one - or more - you can trace that service's history over time with trails. You can also select a given Group.

So give it a go and let me know what you think!

Source: RAJAR/Ipsos-MORI/RSMB

Disclaimer: I built this interactive view using data courtesy of DP Software and Services. Contact Deryck Pritchard for more information.