The latest Rajar data reveals that digital platforms accounted for 20.9 per cent of all radio listening in the last three months of 2009, down from 21.1 per cent in the previous three-month period, but up from 18.3 per cent in the same period of 2008.
Without switchover, the industry will be burdened by costs of broadcasting on both digital and analogue. Commercial radio spends £70m a year on transmission costs - out of total revenue last year of £500m - with around £40m of it going on analogue.
Ennals, in charge of ending UK analogue radio, was quoted as saying that it requires "a step change but it is doable." Broadcasters should provide increased mainstream content on digital, he added.
One critical aspect will be to develop the digital audio broadcasting (DAB) transmitter network to match FM coverage.
The Digital Radio chief is confident of putting a plan in place by the end of the year, with a majority of the funding expected to come from the BBC.
Switchover will also require that DAB radio become standard in new cars. Ennals takes heart in the success of digital TV, which was also initially written off.