He was the second son of George Preston, sixth of Valleyfield, who was created a baronet of Nova Scotia on 31 March 1637.
He was captain in the service of the States General of the Netherlands in 1688, and attended William, Prince of Orange on his expedition to England.
[1] On the outbreak of the Jacobite rising of 1745 the London government sent Lieutenant-General Joshua Guest to take command of the garrison of the Edinburgh Castle.
[1] In any case the aged Preston was active and determined, and (Grant says) was wheeled in an armchair round all the guards, every two hours.
When the Jacobite forces sent a flag of truce to the castle, and threatened, unless it were surrendered, to burn Valleyfield, he replied that in that case he would have his majesty's cruisers burn down Wemyss Castle: the Earl of Wemyss had a son Lord Elcho who was a general in the service of the Young Pretender.