What a shame. I used to live near the Thames in West London and when I heard about the whale being sighted I was pessimistic from the start.

Marine mammals do occasionally appear in the Thames estuary (mostly seals and porpoises) and when it happens the prognosis usually isn't good. The last time I remember a seal being sighted in Isleworth (which is almost at the limit of the tidal river) it had to be put down due to being too weak to make its way back out to sea. This was in the autumn of 1995 and there have probably been other incidents since.

The Thames is a long, narrow and in parts fairly shallow tidal river and unfortunately, it's no place for a creature that belongs in the ocean. Simple as that, I'm afraid.