Red X enforced

[MrsJoshNavidi]

Have seen this message on motorway gantries twice recently. Once in M4 and once on M5. On several gantries, around the Bristol area.

Does anyone know what it means?

I imagine it means that they have cameras and will prosecute if you drive in a lane closed by the red x.

I guess most red x closed lanes aren't 'enforced' and it's sort of left to goodwill that you don't drive in them?

I guess it must be something like that, but it's a weird way of putting it. Though they have to be succinct though, not much space on a gantry!

I've never seen the message before, then twice in a week.