Worked for 3 hours and the power went off... only for a couple of seconds but enough to knock the computer off.
Opened up file and without thinking when 'Autosave back-up enabled, do you want to save changes?' appeared, why did I click 'no'?.... Wasted afternoon, could have been out on my bike all afternoon and achieved as much today... I know I should save to file every few minutes but I get engrossed and forget and normally Time Machine is working in the background but this morning I never got round to taking it out of my bag...
Oh well.