I decided last night that I didn't know enough about the subject, which was perhaps why it was stalling. I couldn't sleep. At 3am I finally got up again and started reading my book on virology. Usually when I do this, read until I feel myself drooping, when I do go back to bed I sleep immediately - but not this time.
Today I spent the morning preparing a class I am taking at the University of Salford next week and then the rest of the time making essential emails and phone calls.
No progress and no words written.