Eliot was born at Port Eliot, Cornwall, the third but eldest surviving son of Edward Eliot, 3rd Earl of St Germans, and his wife Jemima (née Cornwallis). He was educated at Eton College and then joined the Diplomatic Service. He served as Attaché at Hanover from 1849 to 1853, as Attaché at Lisbon from 1851 to 1853, as 2nd Paid Attaché at Berlin from 1853 to 1857, as 1st Paid Attaché at Constantinople  from 1857 to 1858, as 1st Paid Attaché at St Petersburg from 1858 to 1859, as Secretary of Legation at Rio de Janeiro in 1859, as Secretary of Legation at Athens from 1859 to 1861, as Secretary of Legation at Lisbon from 1860 to 1861 and from 1864 to 1865, as Chargé dAffaires at Rio de Janeiro from 1861 to 1863 and as Acting Secretary of Legation at Washington DC from 1863 to 1864.. How many years did Eliot serve as Acting Secretary of Legation at Washington DC from 1863 to 1864?