The doorbell that tricks burglars into thinking you're home - and the boy, 13, who invented it

Smart boy: Schoolboy Lawrence Rook, 13, invented Smart Bell, which calls your mobile when it is rung

A schoolboy is on course for a £250,000 windfall after inventing a doorbell that fools burglars into believing somebody is home at an empty property.



Smart Bell, designed by 13-year-old Laurence Rook, dials the homeowner's mobile phone when pressed, allowing them to talk to whoever is outside their front door.



The device even produces a small amount of white noise to give any unexpected guest the impression they are speaking to someone inside the house on an intercom system.

The invention, which uses an inbuilt SIM card and existing mobile-phone technology, would also allow homeowners to give instructions to drivers making deliveries at their property.



Laurence has already sold 20,000 units to telecoms giant Commtel Innovate and is finalising a deal with an unnamed second company for a further 25,000 units.



When the deal is signed, he will be £250,000 richer.



The teenager, from Whyteleafe, Surrey, said: 'At first I designed the idea because my mum was fed up going to the Post Office to collect deliveries made when we were not at home.

'When I started to develop the Smart Bell, I realised it could also be a great burglar-deterrent.

'Most opportunist burglars ring the doorbell first to see if anyone is at home, but Smart Bell has the perfect way to counteract this.



'If you are out and a burglar comes up to your door and rings the doorbell, after ten seconds Smart Bell will ring through to your mobile phone and you will be able to answer.



'There is a small amount of white noise so it will sound like an intercom and the burglar will never know that you're not actually inside the house.'



Inspiration: Lawrence initially came up with the idea for a Dragon's Den style contest at his school - but wasn't allowed to enter without a prototype

Laurence had the idea for the Smart Bell after his school challenged pupils to come up with an invention for a Dragons' Den-style competition.



Laurence, who won a scholarship to attend private Trinity School in Croydon, South London, was initially unable to enter the contest because he didn't have a working prototype.



But his parents, James and Margaret Rook, then showed his plans to family friend Paula Ward, who was crowned the world's top female inventor in 2004 for designing a web chatroom safety system.



Laurence said: 'Paula thought it was brilliant and sent off the designs to China for it to be made into the actual product.



'I was gobsmacked that she thought it was so good.'



Less than 12 months after the prototype was developed, Commtel Innovate is preparing for the wholesale release of the product and High Street giants B&Q, PC World, Currys and Comet are now set to stock the Smart Bell, which will cost £40.



Riches: Lawrence is expected to earn around £250,000 from his invention which expected to cost £40 from High Street giants including B&Q, PC World and Currys

Laurence is trying to decide what to do with his windfall.



'When I found out I was going to make a quarter of a million pounds, I thought, "Wow, that's a lot of computer games",' he said.



'It's amazing having that amount of money, but I haven't told any of my school friends yet. I don't know what they'll think.



'I'm going to save most of the money – I want to go to university, so I'll need it for that.'



Mrs Rook, 39, an administrator who has two other sons, Matthew, 11, and Oliver, eight, added: 'It's extra¬ordinary but I'm just trying to keep Laurence grounded at the moment.'

