The War on Britain's Roads (BBC Documentary / tabloid tv)

Why did the LCC have this on their card, indicating a "lorry risk zone"?

picture is slightly different as the lorry is yellow and there's a subtitle under it that said "avoid the front-left of lorries near junctions".

The risk zone is not the 'blind spot'. As Charlie says, cyclists often do get hit in the black area, or the red area on the card, but much of that is where drivers of lorries equipped with the more modern equipment must see/should have seen them. Charlie doesn't mention it here, but there's a serious problem with the 'blind spot' defence often used and accepted in court, as areas that aren't, strictly speaking, 'blind' are passed off as such in defence of drivers. I'll leave it to him to explain the rest, as I can't say that I fully understand it.

Obviously, regardless of the technicalities, cyclists should still avoid the front left of lorries at junctions. Whether or not drivers of newer lorries are legally obliged to see them there, an older lorry may not have the equipment, or the driver may still make a mistake. The key aim is to prevent serious or fatal crashes and worry about blame or not later.