In November 1759 the Arundel intercepted a slave transport, the Swift, and found 100 slaves kept in terrible conditions. Although both had been the in the Caribbean long enough to see conditions on the plantations, and discipline in the Royal Navy was notoriously harsh, this seems to have shocked both men, especially Ramsey, and had a profound effect on their thinking.
A plan of the slave trader Brookes, published by the Plymouth Chapter of the Society for Effecting the Abolition of the Slave Trade in 1788
In 1760 Middleton was transferred to the Emerald, where he had an extremely successful year, capturing 16 French boats and privateers, but in December 1761 he was in England, where, aged 35, he married Margaret Gambier. Charles was still on active service, patrolling the Normandy coast in the Adventure, so Margaret went to live in the Kent village of Teston, to be near her friend Elizabeth Bouverie. When he retired from the navy in 1763 Middleton joined her there and for the next 12 years farmed land belonging to Mrs Bouverie. The outbreak of the American Rebellion, and the huge demands on the navy fighting the rebels, the French and Spanish, led to his re-enlistment and he was given command of a guardship in the Thames estuary, not so far from Teston. He seems to have made an excellent impression as he was appointed Comptroller of the Navy in 1778, a post he held for 12 years.
Ramsey meanwhile had followed a different path. Leaving the navy in 1762 he trained as a priest in London and volunteered to work amongst the slaves of St Kitts (then St Christopher). With his medical experience he was appointed surgeon to several plantations on the island and saw to his horror the conditions of many of the slaves. Ramsey lived on St Kitts until 1777, campaigning locally and with letters to the Bishop of London, but eventually he was forced out. Weakened by the struggle, the tropical conditions and a leg wound he had received in the navy he went to join his old colleague Charles in Teston.
In Teston Ramsey quickly converted Mrs Middleton to his cause, Charles already being sympathetic, but he was not there long. Volunteering again for the navy he was transferred back to the West Indies, where he served as a chaplain, reportedly collecting intelligence against the French. Middleton, now influential in the Navy and indeed knighted as Sir Charles Middleton, invited him back in 1781 and made him vicar of the parishes of Teston and nearby Nettlestead.
Both Middleton and Ramsey now entered more forcefully into the political arena.
In 1784 Ramsey published a pamphlet, An Essay on the Treatment and Conversion of African Slaves in the British Sugar Colonies, which was very influential. Public attention was drawn to the subject and several figures who would later be prominent abolitionists , such as the bishop of Chester, Beilby Porteus, were influenced.
Meanwhile, Middleton became MP for Rochester, which he remained for 6 years. In parliament he met the young MP for Hull, William Wilberforce, who he befriended and in 1787 in Teston introduced to Ramsey and Thomas Clarkson, a young firebrand anti-slavery campaigner. It is unclear if it was Middleton who planted the idea of abolition in Wilberforce's mind, as there were many campaigners around the country, but it is possible. Whatever the case, Teston became the centre for the abolition movement, with many meetings of Wilberforce, Porteus and others at Barham Court.
James Ramsey died in 1789, worn out by campaigning, but the Middletons continued. Political activity did not affect Sir Charles's career and he was promoted to Lord of the Admiralty in 1794, and in 1805 he was made Baron Barham of Barham Court and Teston (not bad for the son of a customs collector). He died in 1813, but by then the slave trade, if not slavery itself, was illegal. The slave trade was abolished in the British empire in 1807, ships transporting slaves were to be treated as pirates, and any men captured could be executed.
Through the 19th century the Royal Navy was more or less single handedly responsible for stopping the Atlantic slave trade, partly so as not to give a commercial advantage to their competitors, but also due to enormous moral pressure from the public. Britain's unprecedented control of the seas making this possible.
Astronomical amounts of money were spent. An entire new naval base was constructed on the West African coast in Freetown, modern Sierra Leone, where many sailors lives were lost to tropical disease - the mortality rate was 55 per 1,000 men, compared with 10 for the Mediterranean or Channel fleets. Between 1830 and 1860 there were never less than 6 ships on station, and sometimes over 30, including new paddle steamers, which could patrol the coast much more effectively. An incredible 1,600 ships were captured between 1808 and 1860, and over 150,000 slaves freed. Many, not surprisingly, were not keen to go back only to be enslaved again, and stayed in Sierra Leone.