Confusing motorway signs

[RazerSauber]

This isn't a bashing thread or anything of the sort, just my confusion. I was coming home along either the M5 or M6 northbound last Friday and encountered some peculiar road signs. For mile after mile there were warnings of a lane closure on the electronic gantries which is fine (the 60mph limit for about 20 miles less so). Upon getting to the supposed lane closure, there were older style metal signs on the side of the motorway. The first one said lanes 1 & 2 closed, the next sign said lanes 3 & 4 closed. Interesting. The next sign was back to lanes 1 & 2 closed so I thought someone had made an error on the signs and the sign after said lanes 3 & 4 closed again. I stayed in lane 2 thinking whichever one happens to be correct, I'll only have to move 1 lane at most. I could see cars ahead and behind all moving into lanes 2 & 3 too, presumably doing the same. When the signs ended, guess which lanes were closed? None of them. There was, however, a police stop in lane 1 of the other carriageway. No cones, no highways agency/England vehicles, no highway maintenance vans of any description. Is it seriously possible that they reduced the speed limit of one carriageway for police activity on the other carriageway? And what were these metal lane closure signs about?

[Every day a journey]

‘This sign is not in use’