Then consternation changed to understanding when I realised why they had no unleaded fuel. They're unlikely to have had a delivery since the week before Christmas and - at 99.9p/litre - they're the cheapest place for miles.
This obviously didn't help my cause, as I was still running on fumes with no guarantee of finding another petrol station before my tank started making straw-sucking-in-an-empty-paper-cup noises.
Then it hit me.
And it hurt.
I realised that, despite the fact I've never used it before and thus never considered it to start with, super unleaded is basically regular unleaded with added vitamins and minerals (yes, I know it's more than just that)... so I put £25 of that into the car instead. It was only 104.9p/litre, so not that much different to the cost of regular unleaded at neighbouring petrol stations.
My car will probably never thank me for putting a higher quality fuel into its gullet, but at least I know that my additional £1.20 will probably do my car some good.