Red light cameras

Do red light cameras work on the vehicle that just past it so taking a photo of the rear of the vehicle or do they work for the oncoming vehicle also? Before my fans get excited no I’m not asking because I think I’ve been caught. I did see a vehicle go through on a blatant red light and noticed the camera but on the other side of the road and junction and just wondered if they can be set to work in both directions?

The DCPC came up with this from the trainer who was actually an HGV/ PSV driving instructor who regularly takes candidates into London. Whether it is true I can’t say but it certainly sounds as if it should be what happens.

At certain London box junctions, notably specifically including those with a left or right turn only lane, the red light cameras have been set up to take multiple photos to catch drivers who deliberately use the wrong lane and then leave another vehicle blocking the junction because they have overtaken it.

Probably hogwash but just maybe someone may confirm.