It is a moving event. Her school tuck-box, toy typewriter, ballet shoes, and childhood photo album all depict, with epic simplicity, the days before she was famous. The items touch the spectator unexpectedly - even after all this time.
Centre-stage stands the Emanuel wedding dress that left the world gasping on July 29, 1981, its impact undiminished after three decades. At the other end of five rooms of exhibits is one visitors sometimes walk past without noticing: a wall filled, floor to ceiling, with books.
These are the hundreds of bound volumes of condolence, collected in the wake of the events of August 31, 1997. They brim with signatures and messages. The sea of flowers outside Kensington Palace may have died long ago but here remains the evidence, in innumerable hands, of that outpouring of love and grief.
This week the carpark at Althorp was crammed. Charles, the ninth Earl Spencer, mingled with the crowds, signing copies of the books he has written since his sister's death. One, a slim, silk-bound copy of the incendiary address he delivered at her funeral, sells for £25 ($50).
There were also plenty of other mementoes on offer and the tills rattled merrily - no hint Althorp's Diana industry was about to shut for good. But it has. As the final coaches left the 20,000ha estate, the relics of Diana's life were being packed up in preparation for their return to her sons, Princes William and Harry. First, they make a detour via America to earn their keep - but Britain will see them no more.
In May the 49-year-old peer announced his exhibit "would close worldwide in August 2014", explaining that under the terms of Diana's will her possessions had to be returned to her sons when Harry reached his 30th birthday in September that year.
But the commercial exploitation of "A Celebration" (industry insiders put the box-office gross over the years conservatively at £25million) and the fact only a relatively small percentage of the profits found its way to Diana's charities, has angered some - including, it is said, William and Harry.
- Daily Telegraph