New road signs, M6 - pdc {P}
New road signs seem to have popped up along the M6, at least between Knutsford and Stoke. They have a number on them, somewhere in the 200's range, and the number counts down (or up depending on direction) in 0.5 increments between signs. They are about 18"x12" atop a 3 foot pole, and is standard motorway blue. South bound there is a letter B below the number, north bound it is A.

I thought that they were mileage posts at first, but they seem to be spaced at 1/3 mile intervals, although is probably a metric spacing as the odd one clocks in at 1/4 mile.

Any idea what they are for?
New road signs, M6 - BB
I noticed this the last time I was up there. The posts have the same numbers on as the existing motorway markers (the ones you use when telling the recovery service where you are when you breakdown).

I assumed it was a newer more visible replacement.

Value my car