As the weather has been horrific I spent a bit of time tinkering. Checked the earth, put the Exide back in as it has a bit more cranking power, checked the cam belt and everything lines up correctly. Cleaned the leads and put new plugs in. It's weird, it still could start immediately or could take a few attempts. If it doesn't start then it almost sounds like it coughs or air is expelled and there's a ting noise and it just ends up with the starter spinning. It doesn't generally just turn over like a 'normal' engine would. Once it starts it idles perfectly and when driven is absolutely as you'd expect. It's just the weird starting thing that I dont get.
