A bit cruel enclosure for a lobster (Homarus gammarus)

Agreed, rather small. Looks like the width is about the length of the lobster, or even a little less? And not one hiding spot...

I think that the tank is about 10 cm larger maybe than the lobster. Definitely didn't seem like it could turn around. Wikipedia says it can grow up to 60cm, this definitely felt more like a 25/30 cm long specimen. So I estimate the tank to be around 40/50 centimeters long. I do believe though that this tank wasn't intended for a lobster as this species had been showed earlier in the Aquarium where it had a proper education sign. Here it was next to some seahorses and pipefish.