A worried father has put the brakes on drivers racing past his home by building his own speed camera.

Ray Allott tinkered in his garage for six months to make a fully operational device.

During its first day outside his home, Mr Allott's home-made Gatso, painted luminous yellow to look like a police camera, "caught" 137 offenders.

He says he is happy to hand his evidence to the police - but they have warned he could be committing an offence.

Mr Allott said he built the camera to protect his children Elizabeth, 11, and Laura, two, and other youngsters along busy Forest Moor Road, where he lives in Knaresborough, North Yorkshire.

The 38-year-old has already received inquiries from two schools and a local authority about similar devices.

But police chiefs believe the camera could be breaking the law if it is left obstructing the highway, and said improving safety was more complicated "than simply using cameras".

Mr Allott is now considering having his camera calibrated so that he can apply for Home Office certification, which would make his evidence admissible in court.

The camera is portable and trailer-mounted, so it can be moved if people become accustomed to seeing it in one place.

The device contains an adjustable sensor, which detects vehicles travelling faster than the 40mph speed limit on Forest Moor Road, and takes a picture.

Mr Allott said: "Building it wasn't too difficult, it was making it accurate that took the time. We now have it accurate to within 5mph."

Sergeant Nigel Atkinson, of North Yorkshire Police, said: "Speed detection devices are strictly regulated by the Home Office and require approval by the Secretary of State before any information gathered by them can be tendered as evidence."