A blue sign with a diagram showing a branch off the road ahead and the following text.
Forward destinations: C. London; Brent Cross; Harrow; Watford.
Exit destinations: North; Watford ; A405.
Junction number: 6.
The real sign in this location is of a type affectionally known to road enthusiasts as a "Mr Floppy", in that the branching arm of the diagram indicates the sharp turn at the exit by hanging downwards. What they mean by that name I can't imagine.