Many thanks to an attentive subscriber who told us that updates were no longer arriving by email. Apparently they stopped around 20 April; I have no idea why. This has not affected those who subscribe directly in a feed reader (which is why I did not myself notice). I’m trying to sort this out as quickly as possible, and I hope normal service will be restored soon.
(Of course, if you only subscribe by email, you may not see this …)