I have no info about this but I have been told that on Monday, to celebrate 50 years of the M1, there is to be some kind of cavalcade of period vehicles (junction 8 area?).
My parents back in 1961 used to stand a watch cars go up and down the M1 at around jct 6....with no speed limits and people used to picnic on the hard shoulder. There we so few cars back then that you could wait minutes to see something pass by at 57 mph or slower!
Whew - what a relief - when I saw the thread title in the list I thought there was a 50 limit coming in for the Mi (and not just the road works!) I remember when it opened. Yes, many things have gone backwards since. It was great to make decent progress thenm. Pete