More than 18million digital TV set-top boxes linked to the Freeview broadcasting system must be retuned tomorrow – or viewers could lose key television and radio stations .
At the same time, 7.7 million television sets which have Freeview digital technology built into them will also have to be retuned.
The exercise is the result of major changes to the frequencies used to broadcast more than 50 television channels and another 20 radio stations to rooftop aerials. It is part of a plan to make Channel Five available to a greater part of the country and clear the way for high-definition digital television channels.
Messages have been been shown on-screen alerting people to the technical changes, which will take place tomorrow morning and are expected to be complete by lunchtime. Those who are unable to retune tomorrow can do so at a later stage.
The retuning exercise will mean more than 500,000 Freeview homes will be able to receive Five for the first time. A new channel called Quest will also be available to most Freeview homes, on channel 38.