In 1873 he was offered a baronetcy by Gladstone, and again by Disraeli in 1874; in each case the honour was gracefully declined.
After a period of work in Holland he betook himself to England, where his treatise on lettres de cachet had been much admired, being translated into English in 1787, and where he was soon admitted into the best Whig literary and political society of London, through his old schoolfellow Gilbert Elliot, who had now inherited his father's baronetcy and estates, and become a leading Whig member of parliament.
Lord Palmerston offered him a baronetcy and a seat in the privy council, and the emperor of the French would gladly have conferred upon him some distinguished mark of his favour.
He was educated at Eton and Trinity College, Dublin, and in 1868 succeeded to the baronetcy on the death of his father.
His Son, SIR John Johnson (1742-1830), Who was knighted in 1765 and succeeded to the baronetcy on his father's death, took part in the French and Indian War and in the border warfare during the War of Independence, organizing a loyalist regiment known as the "Queen's Royal Greens," which he led at the battle of Oriskany and in the raids (1778 and 1780) on Cherry Valley and in the Mohawk Valley.