The M531 motorway in a former motorway from the 1980's. It's now part of the M53 motorway, from junctions 5 to 10.
The M531 was originally an unclassified road, then upgraded to and A-road, the A5032. It was then upgraded to Motorway when the Vauxhamm factory opened up in Ellesmere Port, the motorway was needed to keep up with traffic demands. This explains the reasons for the junctions being close together. Also, the M531 is the reason that the M53 breaks apart before J5, then comes back together. The M53 would originally end up in Queensferry or Ewloe , with the M531 coming off between junctions 4 and 5. When the road was extended to accomodate junctions 11 and 12, it opened as M53 bacause the Queensferry plan had been cancelled.
Today, there is still some M531 evidence, such ass the road break before junction 5 and the sign for M531 that hadn't been removed at Junction 8 (it was removed in 2009). There also used to be a bridge for the old M53 design, but it was demolished in 2001.