A-road fork sign
A green sign with a diagram showing an exit branching off the road ahead and the following text.
Forward destinations: The NORTH; Hatfield; Potters Bar; A1 [Hollow square diversion symbol]; (M25).
Exit destinations: Borehamwood; A5135; ; .
At about this point we cross the boundary of Greater London and enter Hertfordshire. From here to the fringes of Edinburgh the A1 is a trunk road.