Miniature solid-state cameras, perched next to the bar in the pole vault or inside the fences for horse-racing, have brought a new dimension to televised sport. The innovation is also cheap. A miniature camera costs about pounds 1,000; a typical 'boundary' camera about pounds 40,000.
Peter Byram, who led the cricket project, first tried the camera in the middle stump, but its view was often obscured by the batsman and he had to plump for the off stump. 'If they get hit hard, the wooden part cracks and the mirror moves. They occasionally get hit so hard the electronics are broken.'
Mr Byram tried sending the image from the crease via a radio link, as do Australian broadcasters. But the picture broke up too often, so he had to persuade the Test and County Cricket Board to let him lay permanent ducts at all six Test match grounds.
The depth of the cable duct depends on the ground. At the Oval, where there is little problem with drainage, the cable sits 8in below the ground. At Lord's, it is 8ft down because the groundsmen have to spike the ground frequently.
The 3.5mm electrical cable links a mobile-broadcast vehicle to the stump. The camera and the electronics to control it fit into a tube made from a lightweight aircraft alloy. The unit, no more than 5in long, fits snugly inside the hollowed-out stump.
The camera lens peeps from behind an aperture less than one-third of an inch across. A light-sensitive microchip, called a charge-coupled device, picks up the image. The camera has two views - one using light from the ground sent via a prism, the other using light bounced off a mirror. The first creates a narrow view looking down the pitch towards the bowler.
The cricket camera was designed to carry its controlling electronics inside the one unit. Other tiny cameras, with their controls in a separate box, can be even less obtrusive. The smallest of these, known as 'lipstick' cameras are the size of a make-up canister.
Remote filming is likely to become increasingly popular. 'Eventually, all you will need is four or five cameras, completely unmanned. You could put all those pictures through a computer and let people pick their view from anywhere in a sports stadium,' Mr Byram said.