So it seems that Blogger have a solution for their recently introduced layout problems.
- Log in to Blogger.
- On the dashboard, select your blog.
- Select the Settings tab.
- Select the Formatting option.
- Scroll down and set Enable float alignment to No.
This will stop Blogger adding those nasty <div clear:both> tags. Everything is explained in this post although I think they might have been better advised broadcasting it a bit further.