Tim Woodbridge, son of Stourhead's historian and former WWII intelligence codebreaker Kenneth Woodbridge, pictured, says heartbroken owner Henry Hoare II flooded the original lake 270 years ago after the sudden death of his son and heir Henry III, aged just 21.

A landscape by artist Coplestone Warre Bampfyld(left) drawn in 1753 which shows features from the lost garden at Stourhead. The arch and statue of the river god beneath the Temple of Flora can be seen. A modern view of the same feature is seen on the right.

An artist's impression of how the lost garden at Stourhead would have looked

The original garden would have featured two smaller lakes to the north and south, with a Chinese bridge crossing the former, a Grand Canal leading to the Temple of Florato the east, and an ornamental pool on the west side in front of a grotto that still stands today.

The remains of the sentinel oak, plus the foundations for the original lakes, ornamental pool and Chinese bridge, were detected during an underwater survey in 2005.

Ironically, the flooding of the lake has preserved the remains, which lie under many feet of a very fine silt.

Woodbridge, 71, said the cost of digging up the Great Lake makes it unlikely that the original garden would ever be uncovered.

TOTAL RECALL

‘PREGNANT’ NEWBORN

USE IT OR LOSE IT

Have more sex & quit smoking... how to protect your penis from shrinking

DIRTY TRICKS

These saucy optical illusions will have you questioning your dirty mind

He added: "Hoare set out to create a lasting legacy for Susan and then for