Looking at your location I'm guessing it's the one near the roundabout with the Harvester on it?
If so then I used to work in it 25 years ago. At that time the forecourt heading towards Chertsey was always set a little more expensive because it got way more traffic from people filling up ready to go on the M25 and they preyed on the fact that no one fancied having to turn right twice on that busy road.
It's amazing what an idiot you can feel holding up so much traffic turning right into a petrol station when there's one on your left!