Poor heading alignment in IE

I just noticed my header alignment is out when I view my individual blog posts in Internet Explorer. It’s fine in Firefox which is why I missed it at the start.

http://www.davidairey.com/blog

It’s fine on the main front page but when the top of the list individual post is viewed the header aligns with the end of the link to the ‘next’ post, rather than being left aligned on a new line.

Any idea?