Well, how can you tell otherwise?

LATER: Lovely email from Ben Hammersley:

I know this! You spin them on their side, then lightly put your finger
on the top to stop them spinning. Take your finger off quickly. If it
remains stationary, it’s hard-boiled. If it keeps spinning, it’s raw.
It works because the raw yolk keeps moving inside the egg, so when you
take your finger off, the whole thing starts moving again.

Finally, I have a use for that. Hurrah!

Hurrah! x 2. Isn’t the web wonderful?