Heriot was appointed jeweller to the royal family, with whom he became increasingly involved, even to the extent of being allowed a room in the Palace of Holyrood in which he could conduct his trade. With the Union of Crowns in 1603, the royal household moved to London. Heriot followed and set up his business there which flourished under the royal patronage. Over the years the king and queen became increasingly dependent upon Heriot not only for his jewellery but also for his services as pawnbroker and money lender (at 10%) in times of crisis; he was in effect their private banker. Heriot died in London in 1624 and was buried at St Martins-in-the-Fields. He had no legitimate children and after a number of small legacies to friends and two illegitimate daughters, he left the bulk of his considerable estate, to the town council of Edinburgh for the erection of a hospital ‘for the education, nursing, and upbringing of youth, being puir orphans and fatherless children of decayed burgesses and freemen of the said burgh, destitute, and left without means.’ From this bequest George Heriot School was established and the Heriot–Watt University was partly funded.