Is this early blight?

[SimpleSimon]

My maincrop potatoes have started looking a bit odd. Not all of them but this is the worst of it...



Is this blight?

[ameno]

It is indeed early blight, but early blight is not "blight".

The worrying one is late blight, which is a completely unrelated disease and far, far worse.
Early blight usually only attacks in dry conditions, especially hot, dry conditions, so bad attacks aren't all that common. As long as the infection is mild (which that is) early blight can be safely ignored. It won't spread much if conditions are too damp and cool for it, it rarely kills the plant, and even more rarely actually infects the tubers (unlike late blight).

[SimpleSimon]

Cool thanks. That pic is of the very worst affected leaf and the rest are much less, some are looking absolutely fine. Good to know it's not terminal

[ameno]

Early blight isn't much of a problem here in the UK, as it's usually too cool and damp for it to grow properly.
Even if hotter countries, it's rarely devastating in the way late blight is. It just reduces the size of the crop as a bad infestation will cause premature leaf fall, which obviously means the tubers won't swell as much.