@Pionir @sellathechemist @ChrisMayLA6 @GeofCox I once again find myself looking at https://grid.iamkate.com/
I don't think there are any days when gas isn't used.
Where I am in the west Midlands gas was 70+% of generation between 11th and 17th October
(Data from https://www.carbonintensity.org.uk)