The sad fate of the London whale had its upbeat side. In the 1870s, a porpoise entered the Thames and swam further through London than last week's whale. The event was recorded, with dismay, by the great naturalist Richard Jefferies.

"Now, just think, a porpoise up from the great sea, past Gravesend, past Greenwich, past the Tower, under London Bridge, past Westminster and the Houses of Parliament, right up to Mortlake. It is really a wonderful thing that a denizen of the sea so large and interesting as a porpoise should come right through the vast city of London.

"What happened? Someone hastened out in a boat, armed with a gun or rifle, and occupied himself with shooting at it. He did not succeed in killing it, but it was wounded.''

The wayward marksman was not a lone hooligan. All wildlife on the river was generally regarded as fair game. Jefferies observed: "The moorhens are shot, the kingfishers have been nearly exterminated, the once common black-headed bunting is comparatively scarce, and if there is nothing else to shoot at, then the swallows are slaughtered.''

Birds - and a luckless stray porpoise - weren't the only victims. Jefferies noted: "Anyone who chooses may watch the water vole feeding on aquatic vegetation. Never mind, shoot him, because he's there.''

But what Jefferies called the "bitterest, harshest and most envenomed'' assault was reserved for the otter. "It is as if the otter were a wolf,'' Jefferies complained. "Has he ravaged the fields? Does he threaten the homesteads? The truth is that the otter is an ornament of the river, more worthy of preservation than any other creature.'' He urged his readers to condemn "the shameless way in which every otter that dares to show itself is shot, trapped and beaten to death."

Pity he didn't witness the reaction to the whale. Not merely tolerated but viewed and treated with a tender concern. Anyone taking a pot shot at the stricken creature would have risked a lynching. Instead, a rescue mission was mounted that would have been unthinkable to the Victorians, even though they probably had the means to carry it out.

Like the protection now enjoyed by otters and most wild birds, the compassion for the whale shows how much attitudes to wildlife have changed, for the better, over the last century.

So we can rest on our laurels? Hardly. The hare, a beautiful animal that poses no threat, is still shot. Many supposed bird lovers call stridently for culls of raptors like sparrow hawks and magpies, as though these haven't a place in nature's scheme. Badgers and grey squirrels are about to be officially persecuted.

While liberated from circuses, animals still suffer imprisonment in zoos, a scarcely less degrading showcase. The conservation role that is now advanced as their chief raison d'etre merely exposes our apparent inability to save creatures in their natural habitat, which we are greedily destroying.

Of the Thames and its wildlife Jefferies wrote: "I think there is not a single creature, big and little, beasts and birds (of prey or not) that should not be encouraged and protected on this beautiful river...'' With a few exceptions, headed by the rat, that goes for every wild creature on our still wonderful planet.