Help! Recent Posts displaying over the posting body

We’ve recently re-built our site and are now running the blog with WordPress: https://www.quba.com/blog

The blog page was just built in a very simple way to begin with, just showing the posts and a small list of ‘Recent Posts’ to the right-hand side.

I was putting some tweaks into the Editor (sorry) to get the author to show at the top of the posts – which I succeeded in after trying a few different pieces of code in various templates. I however seem to have done something which has caused this ‘recent posts’ bit to appear underneath the post title, covering the date, author, tags etc. bit. I’ve been through the code in lots of templates that I may have edited but can’t seem to find what’s causing it.

I’ve searched them all looking for ‘recent posts’ as this is the title so presume that this part of the code must have that in there somewhere – but it doesn’t seem to be anywhere!

The theme that’s been used is Twenty Thirteen. Can anyone shed any light on this?

Thanks.