I finished the hat without needing to buy more yarn!
Here it is blocking over the lid of a cake tin. I had about 7 yards left of the yarn which is lots really...
And this is the detail of the centre which has more accurate colours:
Simple cabled hat (improv.pattern)
Colinette Art (0.6 of a skein) in Ischia (I think)
3.25mm and 4mm needles
I don't think it's worth writing up but I might change my mind. Some things I improvise are just 'mojo' knits - I'm in a slump and need to get my knitting mojo back with something simple but lovely.