Junction 13 of the M40 is the home of oversized checker-board backing to yellow-backed signs!
Early 1970s plan for the junction
If the original preferred alignment of the M40 had been built there would not have been a junction here. Instead there would have been a full movement roundabout GSJ at the A452/A425 roundabout about a mile to the north. However the route of the M40 as built is shown on early plans as an alternative. This alternative would have had a junction slightly to the north of J13. This junction would have been a roundabout GSJ with east facing slips only, just like the half diamond that was built.