William Dolben, the second and only surviving son of Sir John Dolben, was born on 12th January 1727 at Finedon, Northamptonshire. He was educated at Westminster School and Christ Church. Soon after leaving Oxford University he married Judith English at Westminster Abbey on 17th May 1748. She brought with her a fortune of £30,000.
Dolben succeeded his father in the baronetcy on 20th November 1756. He also served as high sheriff of Northamptonshire in 1760–61. On 3rd February 1768, Dolben was elected to represent the University of Oxford in the House of Commons at a by-election. He was an independent MP who supported parliamentary reform and the abolition of the slave trade.
In May 1788, Charles Fox precipitated the first parliamentary debate on the issue. He denounced the "disgraceful traffic" which ought not to be regulated but destroyed. He was supported by Edmund Burke who warned MPs not to let committees of the privy council do their work for them. William Dolben described shipboard horrors of slaves chained hand and foot, stowed like "herrings in a barrel" and stricken with "putrid and fatal disorders" which infected crews as well. With the support of William Pitt, Samuel Whitbread, William Wilberforce, Charles Middleton and William Smith, Dolben put forward a bill to regulate conditions on board slave ships. The Dolben Act, passed 56 to 5 and received royal assent on 11th July.
Dolben's biographer, Nigel Aston, has argued: "No cause was dearer to him than the abolition of slavery, or at least the improvement of conditions for black slaves being shipped to the West Indies on the middle passage. Despite opposition from the merchants of Bristol and Liverpool, with Pitt's support he successfully piloted a bill through the Commons in 1788 designed to limit the number of slaves allowed on a vessel in proportion to its tonnage (initially, for a trial period of a year). Dolben developed a close alliance in parliament with William Wilberforce on the slave trade. He supported in principle the series of abolition bills Wilberforce brought forward in the 1790s."
Suzanne Schwarz, the author of Slave Captain: The Career of James Irving in the Liverpool Slave Trade (1995), has pointed out: "The legislation, more widely referred to as the Dolben Act, specified that the master of a slave ship should have served on one previous voyage in that capacity, as chief mate or surgeon during two whole previous voyages or as chief or other mate in three voyages.... Under the terms of the Dolben Act ships could carry five slaves for every three tons burthen up to a maximum of 201 tons, and one slave for each remaining ton." The act also specified that the crew should be paid a bonus if less than 3% of the slaves died on the voyage.