Save the whale: 'I saw them in the Pacific but you don't expect it in London'

Gloria Parfitt had been disappointed when she went whale-watching off the coast of Maine last summer. There in New England, at the home of Captain Ahab, the leviathans had refused to play ball, remaining stubbornly hidden from view.

Yesterday, as she took a break from work for a stroll around Battersea Park in the January sunshine, she finally got to see her whale. "This is just fantastic," said the 50-year-old nutritionist who had taken her place along the Thames embankments with hundreds of other opportunistic whale spotters.

Each time the northern bottle-nosed whale emerged from the water to blast spouts of water from its blowhole 20ft into the air, the crowd gasped and applauded. High above, three helicopters from television news channels hovered. On land, the London Evening Standard, unsure of the whale's sex, had already christened it Pete after the cross-dressing former pop singer Pete Burns, currently on Celebrity Big Brother.

On the water, press photographers in chartered boats formed an impromptu flotilla, a bank of lenses trained on this unlikely new aquatic celebrity.

On the Chelsea embankment, traffic slowed from its usual crawl to complete gridlock as white-van men stopped to take pictures on their mobile phones. Eddie Peters, 70, was out for a constitutional when he spotted the crowds. "Something like this brings hundreds of people together in a spirit of friendliness I haven't seen since England won the World Cup or the end of the war," he said.

Joe Darrall, 66, had been watching the lunchtime news at home in nearby Pimlico when the whale report came on. A veteran of the merchant navy, he is no stranger to the sight of large sea creatures, but he still came down to the river bank. "I saw quite a few whales, dolphins and flying fish in my time, but that was in the Pacific," he said. "You really don't expect them in the centre of London."

The first sightings of the whale were made by fishermen in the Thames estuary on Thursday. At lunchtime yesterday it was spotted emerging from under Westminster Bridge, out from the House of Commons, where it was thought to be chasing a shoal of sprats.

Paul Jepson of the London Zoological Society, part of the unofficial rescue team, was growing gloomy over the prospects for the whale. The marine mammal specialist had examined the whale from a launch. "The prognosis is poor," he said. "We can't be sure why this whale is so far off its normal territory. It may be sick or diseased."

While its frequent surfacings, rolling and blowing had been entertaining the crowds, they were providing Mr Jepson with anxiety. "There is no purpose to its movements, it is completely random. The chances of it making it all the way to the North Atlantic from here are slim - a big, big if."

As the tide reached high water and darkness fell, the whale showed little sign of returning to sea. For those making a detour to the river bank it meant a rare glimpse of a majestic creature in the heart of the capital. But, for the whale, every minute after high tide meant danger as the prospect of it beaching in the shallows grew more likely.