I was merrily typing away on the last thread, not that I'm making much sense and then I tried on the last new thread. I think someone's trying to silence me 
I need to rewatch to examine Chloe's reaction because if she's embarrassed or shocked by the revelation then it means that despite the unknown DNA match, it must be someone known to her even if it's from the mists of time.
My head is stuck on some convoluted theory that somehow involves John Corbett (previously McGillis) his mother Anne-Marie McGillis, missing and then deceased, but still a presence via Jo's photograph, and who was close to Ted; his father Anthony McGillis, who we're told was dead but who may have disappeared into witness protection or gone off to do undercover police work or something, and the relatives in Liverpool who adopted John. They're Sorcha, his Aunt and her husband, Robert Corbett. We know nothing about them, if they had any other children etc. or their general background.
Yes, I have been on the fandom site 
but, oh, looking further, John's father was a carpenter and said to have been killed by loyalist para militaries. So what the Corbett plot link could be, I have no idea.
I'm also awaiting a big thing about Philip Osborne the Chief Constable.