Freeview offers around 30 channels for a flat fee of around £60 -- the price of the set top box -- and is converting viewers who had previously shunned cable and satellite services to digital television.
Over 2m homes now receive the Freeview service, just 13 months after it launched in October 2002.
Freeview will receive a further boost in the New Year when Disney launches its general entertainment channel on the service, marking the US broadcasting giant's first free-to-air channel in the UK.
Many of these viewers are believed to be middle class, which has been the mainstay of BBC Two's audience, and are said to be tuning into multichannel services available on the platform, according to new figures from audience research firm Barb.
The channel's year-to-date share of the total ABC1 adult audience is around 11.5%. This compares to 12.4% in 2002, 12% in 2001 and 2000 and 12.1%.
BBC Two is not the only channel to have suffered. Its terrestrial rivals have also lost middle England viewers at the hands of Freeview's success. BBC One's share of ABC1 viewers is down 3.8%, ITV 1's share is down 2.7%, Channel 4's has fallen 1.6% and Five lost 0.2%.
BBC Two is set to suffer another blow when its most popular show The Simpsons moves to Channel 4 in the New Year.
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