Apprenticed to a merchant at 15, Heathcote traded in London as a Spanish wine merchant, having large transactions with the East Indies and with Jamaica, where he handled government remittances. He played an active part in founding the Bank of England of which he was twice governor. A staunch Whig under Queen Anne, in 1710 he was appointed one of the nine trustees of the Silesian loan to the Emperor for carrying on the war against France, to which he contributed £4,000. Shortly afterwards, he headed a deputation from the city against the dismissal of the Whig ministry.
In the list of the 1715 Parliament prepared for George I, Heathcote is classed as a government supporter with the comment:
Homme fort riche. Il étoit lord maire de Londres du temps de procès de Sacheverell. C’est un homme fameux dans son espèce. Il est fort haï des Tories.
Informations were laid before the Government that in May 1715 Jacobite mobs planned to murder him and the other Whig magistrates and set fire to their houses.
One of the richest commoners of his time, with a fortune estimated at £700,000,
The grave Sir Gilbert holds it for a rule
That every man in want is knave or fool,
and put him into the Dunciad as starting
From dreams of millions; and three groats to pay.
The 1st Lord Egmont remarked that the Ostend Company would never have been set up (in 1722) ‘had it not been for the avarice ... of Sir Gilbert Heathcote and the rest’ of the East India Company assistants, who refused the Emperor a reduced rate of interest on the Silesian loan.
