GeoGraph - photograph every grid square

Road sign from the past or the future?

This sign, seen in April 2009, at the junction of the B7078 (which used to be part of the A74) with the B740 appears to show the way to the M6 North. But the bottom half of the sign is missing, as if an old sign has been covered up with a new sign, and part of that has gone. The new sign would show the route to the M74, which is correct. But was the M6 ever in southern Scotland? This subject is covered at Link