In 1788 the whole nation was thrown into turmoil as the King was declared ‘mad’ after the onset of a mysterious illness, which we think now was probably porphyria. This is a hereditary blood disorder that in serious cases can cause temporary mental derangement.

At this time the King still took a vital role in government, approving Parliamentary papers and appointments. Uncertainty over the state of his mental health led the Opposition – supported by the King’s own son, the Prince of Wales – to call for unheralded Regency.

However, largely due to his own strong constitution (and with little help from his doctors) the King recovered after a few months. From this time onwards his illness and brutal treatment – which included incarceration at the White House, strait-jackets, leeching and emetics - cast a shadow over Kew.