Motorway gantry sign
A gantry spanning the motorway with blue overhead signs indicating one lane exiting and the other lane continuing ahead, and the following text.
Left lane destinations: M25 e ; Dartford M11; Maidstone M20; Westerham A25.
Right lane destinations: M25 w ; Heathrow [Airport symbol] M4; Watford & M1; Reigate A217.
Change Route: M25 Dartford or M25 Heathrow
Clockwise or anticlockwise, it's up to you. And unless you're in a rush, it doesn't matter - the M25 is a big circle so both directions will get you where you're going in the end.