Ros Butt wrote:
Any thoughts as to whether to keep the greenhouse door closed during a
'full smith blight alert' on these warm humid days when it's not too hot?

It has an automatic top-opening vent for ventilation.

We got blight in the greenhouse really early last year, for the first time.
I'm not sure how much help closing the windows would have been, though.
I would have thought lack of ventilation would be just as harmful, as then
there's nothing to stop the spores settling if they get in