Oops, I've just worked out what the problem was. I only have one camera in my scene but the production frame (which I didn't know about until now) was too high. I hadn't moved it though as I didn't even know what it was before. Well now I know to display and check the production frame before rendering in future.

Thanks for the reply and sorry to answer my own question. :lol:

Here's my little scene anyway, after framing.

Cheers.