London analogue TV signal switched off
Analogue television is being switched off in London, 75 years after it was first invented.
The digital switchover means that from now on, viewers will need to use Freeview, satellite or cable.
BBC One, ITV1, Channel Four and Channel Five stopped transmitting on analogue overnight. The BBC Two signal was stopped earlier this month.
An estimated 12 million television sets are affected in the London area, but most homes have already switched over.
The process to turn off the transmitter, which is being managed by communications infrastructure firm Arqiva, began at midnight, when BBC director general Mark Thompson turned off the switch.
The turnover means people will need to convert televisions to receive the digital signal and Freeview viewers also need to retune.
"What we do know is that most people make the transition from analogue to digital TV quite successfully," said Deborah Bain from Digital UK, which is managing the switchover for the UK.
"Some older and disabled viewers will need extra help and what we do know is that people really value face-to-face advice which Digital UK offers at roadshows and advice points."
Roadshows have taken place throughout the city to help people who are yet to make the change.
Advice points, run by volunteers, are also available in local communities and there is a hotline for people who want information.
Bill Taylor, from Digital UK, told BBC Breakfast that so far more than 23 million homes will have switched over.
Northern Ireland, Kent and the North East are still to switchover.
To mark the switchover the Crystal Palace transmitter, in south London, will be lit up on Wednesday night with 200,000 watts of energy efficient lighting at a ceremony attended by Sir David Attenborough and DJ Chris Evans.
Television broadcasts in London have come from the tower since 1956.
The first regular TV service began on 2 November 1936 when the BBC broadcast from Alexandra Palace.