Screens went blank early this morning in a Cumbrian town, signalling the start of the national switchover from analogue to digital television.

At around 2am today BBC2 ceased broadcast in analogue in Whitehaven, which is acting as a pilot town, paving the way for a national rollout.

By 2012, viewers throughout the UK will no longer be able to watch BBC, ITV, Channel 4 and Five without buying a digital box and, in many cases, a compatible aerial.

Families may have to spend £150 on new equipment.

Set owners who have not already done so will have to buy a £25 box for each television they own, as well as more than £100 on a digital video recorder.

But organisers Digital UK claim the cost will be worth it, promising better reception and at least 18 channels as standard, including BBC News 24, Film Four and CBeebies.

Under a help scheme, free or subsidised digital television equipment will be available for the elderly, disabled and the unemployed.

In Scotland, the changeover will take place in three stages. Next year, viewers in the ITV Border region will be first to have their analogue channels switched off.

Viewers of STV North (formerly Grampian) will be next, in 2010, followed by STV Central in 2010-11.

Later this month, Digital UK will send a leaflet to every household in Scotland telling them about the switchover and what they need to do.

James Purnell, Culture Secretary, said: "Digital switchover is essential if we are to ensure universal access to quality broadcasting.

"While more than four in five UK households have already made the transition, switchover will complete the process and prevent millions of people being stuck in an analogue ghetto."