As of 2017, how many British Prime Ministers served in the military with the rank of general?

Britain has had two Prime Ministers who have served in the military as generals. William Petty, known as Lord Shelburne, was Prime Minister in 1782–83. He had served in the army during the Seven Years' War, becoming aid-de-camp to King George III, with the rank of colonel. After the war he was promoted to major-general in 1765, lieutenant general in 1772 and full general in 1783.

The second Prime Minister was Arthur Wellesley, the first Duke of Wellington, rising to the rank of field marshal. His military experience began during the Flanders Campaign, part of the French Revolutionary Wars, in 1794. Later he served in India between 1799 and 1803, and promoted to major-general. During the Peninsular Campaign, Great Britain invaded Portugal and Spain to drive out the French and Spanish as part of the Napoleonic Wars, he was awarded the rank of field marshal in 1813. Wellington served as Prime Minister twice, in 1828–30 and 1834.