In 1703, the house was inherited by the colourful financier John Law who successfully speculated in foreign-exchange deals when he returned from Europe, where he had fled after a duel.
Law had ties with the French government and banking systems, and subsequently set up a company which would develop French interests in the "New World" of America.
He's acknowledged as the first millionaire, if such things are possible - although his fall was as sudden as that of many wheelers and dealers today.
When France devalued its currency in 1720, Law - the controller-general of finance - watched the economy collapse. He was exiled and died in Venice nine years later.
In subsequent centuries, Lauriston Castle underwent many changes as new owners put their stamps on it (the exceptional library was added in 1872).
However, in 1902, William Reid, his wife, Margaret, and her unmarried brother, William Barton, took possession and their home is the handsome "castle" we see today. Reid's successful cabinet-making and furniture company specialised in fitting out luxury liners and railway carriages, and Mrs Reid's family were sanitary engineers. Hence Lauriston had the most up-to-date central-heating system of its time, good plumbing and fittings which look lifted from the most elegant vessels of the day.
Being childless, they indulged themselves by acquiring antiques, colourful carpets, luxurious furnishings, Blue John - the breathtaking collection - and paintings.
They were also nice people, according to contemporary accounts: Mr Reid was described as "the possessor of rare gifts of knowledge, sympathy and generosity"; Margaret - a gifted musician, fluent in Italian, a Fellow of the Society of Antiquaries of Scotland - was "deeply interested in her native city and all that concerned its welfare".
The Reids and Barton made a generous pact: the last surviving member would bequeath the house, contents and property to the nation, which happened at Mrs Reid's death in 1926.
On the day I was there, two elderly gentlemen were playing croquet on the vast lawn from which there is a view of the Firth of Forth.
It felt like I was stepping back centuries and I persuaded myself that I could live happily in the library with its leather-bound volumes, stained glass, deep chairs and that view.
Oh and the connection with New Orleans? That dates back to Law who - while helming French interests in the emerging America - ordered the construction of that city. Although, again, this story sounds contemporary: he over-valued the land, which led to wild speculation.
When the company collapsed, Law was dismissed by the French regent, Philippe d'Orleans, who gave his name to the city.
That explains the New Orleans connection ... but the Japanese garden? I never did figure that out.
CHECKLIST
Getting there: Cathay Pacific offers daily flights from Auckland to London via Hong Kong. Special fares are available.
Further information: For more on Lauriston Castle, see edinburghmuseums.org.uk.
For general information on visiting Britain see visitbritain.co.nz.
Graham Reid flew to London with assistance from Cathay Pacific.
