Keith Mackenzie, racing producer of the Grand National (BBC1 Sat), on filming the race: 'There are five outside broadcast units and about 200 people involved. The units arrive three or four days before the race, but work on scaffolding and cabling began a month ago. We have 33 cameras, 23 of which are used for live coverage of the race, the rest taking offbeat shots such as low angles of the landing side of the fences. When we replay the race, we cut in relevant material from these cameras to illustrate the significant incidents. This year, we've introduced a camera buried in Becher's Brook looking towards the runners and there will be a Steadicam with the horses as they parade. Because of the shape of the course, we have to use three commentators, installed in the grandstand, at fence three and at Becher's.
'The nightmare scenario is losing power from both the mains and our back-up generator, which would leave us with no pictures. Or losing a camera for some reason; some years ago a kind spectator disconnected the camera at the Canal Turn. Now we dig trenches and bury the cables so no one can get at them. If all goes well, everything will be dismantled in a couple of days, and then it's off to cover the European Formula 1 Grand Prix at Donington Park next weekend.'