The BBC said more than half a million of those were aged over 30, outside of its target listenership of 16- to 29-year-olds, although the station's average audience age is 32.
Radio 4's audience was broadly steady, on 10.9 million, as was the breakfast listenership for the Today programme, just under 7.1 million.
Partly thanks to the proliferation of independent radio stations, combined with the extra time spent sitting in traffic jams, radio listenership has risen by a quarter in the past five years.
The statistics of readership or listenership for printed and telecommunications media may be available.
The presence of stars such as Phil Harris, Fred Allen, Bing Crosby, and Kate Smith on CBS swelled the network's listenership.
His critics, whether members of the famously outspoken and change-resistant Radio 3 listenership or media observers who tend to judge the performance of a broadcaster by the crude measure of audience scale, have raised the volume of their dissent to a new high.
Along with Grimshaw's move to breakfast, the changes are designed to help bring the average age of Radio 1's listenership down from 32 to the station's target audience of 15-29 year olds. 15-29 year olds
For many people, Christmas begins on Christmas Eve when a single clear-voiced treble from the Choir of King's College, Cambridge, sings the first verse of "Once in Royal David's City", a heart-wrenching moment, audible via the BBC World Service to a potential listenership of 40 million.
Having recently jumped ship from the ITV newsroom to the BBC, among Katie Derham's many tasks over the coming months will be winning over the traditionally conservative listenership of Radio 3, where she's been handed the main afternoon slot.
Radio 1 is seeking to reduce the average age of its listenership from 29 and is prepared to lose long-standing presenters in order to appeal to a younger audience.
So long as there's a Radio 2 listenership and subscriptions of Mojo magazine still coming on strong, country and folk whether contemporary or relatively nostalgic won't be knocked off its perch for quite some time.
