More than 1m TV sets are at risk of going blank when the London digital switchover begins next week, the body in charge of the process has warned.

Digital UK executives said that with just seven days left until switchover from analogue to digital TV begins in the capital, more than one in London ten households are not ready as their TV has not been converted.

Despite a huge advertising campaign and about 400 roadshows telling people that digital switchover begins in London from Wednesday 4 April, Digital UK London manager Deborah Bain said some people have left it until the eleventh hour.

"We know from previous switchover experience that some people just leave things until the last minute. Well over 90% of people have already ensured the main TV set is ready for switchover or digital, but we are now trying to reach people who have forgotten about the second or third set in the kitchen or bedroom," said Bain.

Although switchover has been a success so far since it began in Whitehaven in 2007, Bain said that London is different because of its greater ethnic diversity.

"More than two-thirds of the UK has already switched, and we are confident London will be a success. But there are changes we have made to what we do such as ensuring the details about switchover is translated into around 22 different languages," she added.

She also said that extra staff have been taken on to handle phones in call centres when London switchover begins with the turning off of the BBC2 signal on 4 April.

"Most people will find the process straightforward, but some may need a bit of extra help, so we will provide advice and assistance throughout the switchover period," added Bain.

London is the most populous area to switch, with 33 local authorities to deal with and about 12m TVs.

Digital UK has a £201m budget for its marketing effort to persuade people to switch to digital TV across the country, but last summer it estimated it will come in £55m under this figure by the time switchover is completed in 2012.

Viewers can find out more on Digital UK's website, www.digitaluk.co.uk, or by calling its helpline on 08456 50 50 50.