There is one key difference. The incumbent in the White House gets a maximum eight-year stretch. In the British capital, the monarch's official London residence has been home to Elizabeth, princess and queen, since 1937.

Time enough, then, to shape the garden. But what kind of garden?

Remarkably, the first serious chronicle of the palace garden has only now been published. Written by the garden historian Jane Brown and photographed by a veteran landscape photographer, Christopher Simon Sykes, ''The Garden at Buckingham Palace'' (Royal Collection Publications, $55) reveals a tranquil 40-acre landscape behind the iconic east face of the palace.

The entrance is a place where tourists gather to see the changing of the guard. In time of national crisis and celebration, Britons form a tide that washes from the palace entrance to the Victoria Memorial and down the Mall. But out of sight, just a few hundred feet away, the queen's back yard remains a silent cove.

It is marked by a large lake, a sinuous path that circles through groves of historic trees, and a clipped groomed lawn, famous for its summer garden parties. There are a few horticultural pearls: the rose garden developed around the wisteria-clad pavilion; the drifts of spring bulbs allowed to develop in an unmown meadow; and a 500-foot-long flower border developed only in recent years by former head gardener Mark Lane.

But revealingly, in a nation where gardening is akin to religion, Brown does not speak of the palace garden as the pinnacle of horticultural artistry. She does not record the queen as a hands-on gardener or interested much in revamping tired or boring parts of the grounds. There seems to be no fruit and vegetable garden.

By contrast, her son and heir, Prince Charles, has taken a highly active role in developing both ornamental and kitchen gardens at his country house, Highgrove, in Gloucestershire, and has become a leading proponent of organic gardening and farming.

The London palace garden passively performs other roles: as a place to walk the queen's corgis, as a landing pad for the royal helicopter and as a wildlife sanctuary. It seems little different from one of the city's leafy public parks, better groomed perhaps but still rendered ordinary by plane trees and bedding geraniums. An actual visit might change that view. (Our invitation appears lost in the mail.)

As Brown explains, the royals have had an ambivalent relationship with Buckingham Palace and its grounds since the grand residence first was bought from the widow of the Duke of Buckingham in 1763 by George III. The wars with France and the United States left little money to spend on a grand garden. When the dissolute George IV came to the throne, he engaged the brilliant but free-spending architect John Nash to rebuild the palace. The costs were scandalous, and on the king's death Nash's plans for the garden were jettisoned, along with Nash himself.

The next monarch, William IV, loathed the place and offered to give it away. Buckingham Palace's fortunes seem to ride on his successor, the young Victoria, who came to the throne in 1837 and married Prince Albert in 1840. Albert was a gifted amateur architect and designer as well as patron of both the arts and science.

Under his direction, the garden at Buckingham Palace might have attained all the grandeur and extravagance of the Victorian garden, with elaborate Italianate terraces and parterres, and walled kitchen gardens of extraordinary bounty. But, alas, he died prematurely, sending his widow into a paralyzing grief, and she retired to Windsor Castle and other country residences where Albert's memory burned brighter than in London.

The grounds were tended, but at the queen's insistence not improved. Her son, Edward VII, loved gardening and flower shows and planting ceremonial trees, and his wife, Queen Alexandra, installed the pavilion that today anchors the rose garden.

Brown argues that the next king, George V, heralded the age of a modern monarchy whose public duties precluded great changes to the palace garden. ''The time for garden-making here was past; from now on it would be rather more of a confirmation of gardening virtues, of the careful management of plants in their setting,'' she writes.

A delightful half-timbered pavilion built by Prince Albert was torn down in 1928. When Edward VIII came to the throne in 1936, he might have turned Buckingham Palace into a mirror of the great Rothschild rhododendron garden at Exbury -- Edward loved rhodos -- but he gave it all up for Wallis Simpson. His brother, George VI, came to the palace with a similar interest in gardening, and his wife, Queen Elizabeth (later, the Queen Mother), was a bona-fide plantswoman who later planted many fragrant shrubs about the place. (Her brother, David Bowes-Lyon, was a leading figure in Britain's horticultural establishment).

In the long reign of Queen Elizabeth II, seven head gardeners have installed and maintained new plantings, particularly of trees and shrubs. Mark Lane, until recently the head gardener, developed a long border of annuals, biennials and perennials, a decorative device that has been around for at least a century in other English gardens.

Lane, who worked at the palace since 1979 and became head gardener in 1992, won the confidence of the queen, Brown writes, and she has approved ''planting schemes he has put forward, particularly in bringing a more personal, human scale to the areas beyond the lawn.''

Queen Elizabeth's legacy at the palace garden may be more in recognizing the grounds as an ecological haven in the midst of a city of 7 million people. Her husband, Prince Philip, has an abiding interest in environmental protection and co-founded the World Wildlife Fund. The late ecologist David McClintock monitored the natural history of the garden for 40 years, and recent gardening practices have helped to foster an increased wildlife habitat. A two-year survey in the 1990s found 287 species of beetle, 630 species of fungi, and a rich bird population that includes wrens, hedge sparrows, robins, thrushes and wildfowl drawn to the lake.

It would have been unseemly, one supposes, for Brown to have conjectured about the garden's future when Prince Charles becomes the palace's next occupant. But given his organic gardening activism, his arrival might provide the moment that Buckingham Palace's garden has been waiting for, as a place reflecting current trends in gardening: sustainable naturalistic designs that please the eye and also provide shelter for wildlife.

Then again, he may follow in the footsteps of some of his predecessors, viewing the palace garden not as a place to develop a bold personal landscape but, as Brown puts it, ''a green space of innocent enchantment.''