Sigh. I guess it was about time. And truthfully i knew i was taking the piss a bit by 'taking a punt', thinking in the back of my mind that it wouldnt really matter because i already have too much beer anyway. Still, sad to see it die (and possibly have to dump some equipment in the process).
So, i toasted as per the instructions and dumped 100g or so of Dessicated coconut in to the fermenter. Nowhere can i find any instructions on how to sanitise this stuff for this purpose (although plenty of people are talking about adding it) but sure enough a couple of days later the delicious porter smells like paint stripper and is sporting a thin white film. Apparently this is an Acetobacter infection (or looks a lot like it) - it basically turns the alcohol in to vinegar. I've had this once before thanks to summer brewing a 25L lager kit and a fruit fly finding its way in. Very sad times pouring that one away. but from experience you dont want to drink it, even though you still can.
So i suppose in some ways all is not lost. 6L of Dark coconut malt vinegar might make a good Christmas gift for someone.
someone i hate.