Henry John Temple, 3rd Viscount Palmerston, KG, GCB, PC (1784–1865) served as Home Secretary, Foreign Secretary and twice as
Prime Minister. He was in government office almost continuously from 1807 until his death in 1865, beginning his parliamentary
career as a Tory, switching to the Whigs in 1830, and concluding it as the first Prime Minister of the newly-formed Liberal Party
from 1859. He was Foreign Secretary when he wrote the letter above.
Palmerston's country estate was Broadlands, on the edge of Romsey, and he was probably acquainted with Josiah George.
Further reading:
Wikipedia article on Palmerston