When the M40 motorway was opened, the A423 and the A4130 both lost trunk road status, and that part of the A423 was renumbered A4130.
When the M40 motorway was opened, the A423 and the A4130 both lost trunk road status because the route from Maidenhead to the Coventry was transferred onto the M40. That part of the A423 was renumbered A4130.