I've just noticed that the permalink structure on my site has changed, I've tried the usual stuff (flushing permalinks etc) but to no avail...

The original structure was

mysite.co.uk/blog/some-title

but it's now become

mysite.co.uk/some-title

External links work ok, despite having the original structure, which is ok, however there's a clash with an custom post type archive page that shares the same slug as one specific blog post, the custom post type is now showing rather than the blog post I need..

I haven't made any changes to the permalink settings, or any of the theme files - does any one have any ideas?

Thanks