Unfortunately, to completely wipe the error, I had to go into each and every Post and delete the extra 'r' in the Posts.
Next time: make a dummy new thread with the corrected title; merge with the other, selecting the correct title and ticking the box to change all post titles to match; delete dummy post.
Generally, spellcheck grabs small errors like that and I notice them. For some reason, I missed it entirely this time round. I'm usually fairly pedantic when it comes to spelling words and i instantly notice the dreaded red line under a misspelled word when i Proof what I've typed before I hit the Post Button.
Musta been true Christmas Madness for me to miss it that time.
Bembo is Jephs Alter Ego.