British Prime Minister Lord Palmerston has enjoyed a rakish reputation as a womanizer, a careless aristocrat and the apostle of big-stick diplomacy. His lengthy life linked the American Revolution and the Assasination of Lincoln, the French Revolution and the birth of the future of King George V, the age of Pitt with the days of Gladstone and Disraeli. His political career brought him three times to the Foreign Office and twice to the Premiership. He set out as a dutiful Conservative, became the darling of Radicals trhoughout Europe, and ended his career as ''Old Pam'', the personification of British courage and lion-heartedness. But there was more Palmerston than bluster and patriotism, as Judd clearly shows in this sympathetic, but critical, biography.