Things are ok. Some relatives came up to visit so I've been pretty busy. The last two weeks have also caught up with me and I'm really tired.
Dad got moved off step down yesterday, he'd picked up a bit of a chest infection and a possible infection in the csf which slowed things down a little. Nothing serious and they went after it with IV antibiotics. Yesterday and today he has seemed much less tired, doesn't just lie there with his eyes closed, so the headaches are starting to abate somewhat. He's also getting fed up of the hospital which is a good sign.
As far as what caused it - they are saying it was most likely an aneurysm in the base of the skull, and that it was a heavy bleed. Another scan yesterday still failed to locate the source, so they are going to do another one in about week. I think they'll keep looking until things have gone absolutely back to normal in there and give up if they can't find it then.
His own circulation of csf seems to be back to normal, they did do a lumbar puncture a few days ago to look for infection and to relieve a little pressure, but no issues since then. He's very weak, he's going to need rehab/physio to get back to being able to walk any distance and he needs a little help to readjust his position. They are also broaching subjects like work and driving license, we'll have to see what they say about the latter, I suspect he might lose it for a while.