It's been on it's way out for weeks but would come and go. It would grind (like when you turn the key too far when the engine's already on). Then it started getting worse and would sound like it's trying but not actually start (like you'd run out of petrol). A few goes and it would get there eventually. Again, it would come and go, sometimes it would start without an issue.
On the weekend it died completely, there's nothing at all, not even a tick tick like you get with a flat battery.
I think you might be right