It's all covered in greeny lichen stuff. I've had a go with a wire brush but doesn't get anywhere near clean. I'm not too bothered but wouldn't want green stuff on my clothes and it makes a crappy first impression.
I don't really want to spend loads of time on this as I am lazy and would rather be tending my veg patch.
Any cunning tips for things to splash on it to make a quick improvement for the summer?