changing places Canaletto's Greenwich Hospital

Few artists have left such detailed images of Britain as the artist Canaletto who came here in 1746 from his home city of Venice. Domestic demand for his paintings had faded away while his much-valued English clients had stopped travelling abroad on their Grand Tour because of the War of the Austrian Succession. If the patrons wouldn't come to him, then clearly Canaletto had to go to them - and hence his nine-year stay in this country.

His enchanting views of Georgian England depict a world of order and elegance where the sun apparently always shined. The seamy side of life - the squalid "Gin Lane" of his contemporary William Hogarth - is conspicuously absent from his work. He was the Saatchi and Saatchi of his time.

Not surprisingly, Canaletto was particularly drawn to the river Thames, which must have reminded him of the Grand Canal in Venice. Many of his paintings show a bustling highway from which more than 30,000 watermen earned a raucous living.

This view from the Isle of Dogs shows Wren's Royal Naval Hospital and Greenwich Park on the horizon. Wren himself always claimed that this was "the finest view in Europe" and I suspect that Canaletto would have agreed with him. The gleaming whiteness of the Portland stone contrasts with the more murky colouring of the river. Canaletto produced this masterpiece in 1752, the very year in which the Royal Hospital had finally been completed, nearly 30 years after Wren's own death.

Today, little has changed - apart from the Thames itself - which is now barren and emp-ty. The silent highway really has become mute as other forms of transport and industry have grown up since the middle of the 18th century. The watermen have been transformed into cab drivers.

But the real changes have taken place behind Canaletto's back with the construction of Canary Wharf whose silvery tower shimmering in the sunlight would surely have called forth another of the Venetian's masterpieces.

However, even Canaletto, praised above all for the topographical accuracy of his representations, couldn't resist just a bit of artistic licence. Look at his portrayal of Inigo Jones's Queen's House, the Palladian delight completed some 60 years before Wren had begun work on the Royal Hospital and sandwiched between the later buildings. In his desire to emphasise the grandeur of the Hospital, Canaletto shows it as puny and insignificant. In reality, the Queen's House is a splendid and eye-catching gem. In other words, not even the work of a master like Canaletto can be taken at face value.