M6 - speed camera chaos

It was interesting to read that thousands of drivers have been caught out by the speed cameras in the roadworks on the M6 near Carlisle.

I drove through those roadworks last week and was amazed. There is no apparent reason for so many drivers to be fined.

However, I was concerned to see how they had erected the actual speed signs.

I was under the impression that speed signs had to come in pairs - one on each side of the carriageway. In these roadworks there's often just the one.

Can someone confirm this is true? (I'm about to contact an expert who will be able to tell me).

If so, it looks like thousands of motorists will have their fines repaid. Maybe.