Britain banned its slave trade in 1807, not slavery itself

Britain’s Abolition of the Slave Trade Act received royal assent on 25 March 1807 and made it illegal from 1 May 1807 for any British ship or British subject to trade in enslaved people. It ended Britain’s part in the traffic, not slavery: people already enslaved in British colonies remained enslaved for another generation.

The scale of what the Act stopped is easy to lose in the word “millions”. The National Archives estimates that between 1640 and 1807 Britain transported 3.1 million Africans, of whom about 2.7 million arrived; roughly 400,000 people died on the way, mostly on the Middle Passage. Britain and Portugal together accounted for about 70% of all Africans carried to the Americas.

Abolition came in stages rather than in one vote:

Year	Measure	What it did
1806	Foreign slave trade law	Barred British traders from supplying foreign plantations
1807	Abolition of the Slave Trade Act	No British slaving voyages after 1 May
1808	1 March deadline	No more enslaved Africans landed in British colonies
1833	Slavery Abolition Act	Began ending slavery itself
1838	End of “apprenticeship”	Full emancipation

The first step was sold on commercial grounds. Bristol Museums’ history of the campaign calls the reasoning purely economic: cutting off foreign plantations’ supply of enslaved labour meant less competition for produce grown in British colonies.

Enforcement was by penalty. A trader caught after the deadlines faced a fine of £100 for every enslaved person aboard, about £5,000 each in today’s money by the museums’ estimate, and the ship was confiscated.

What the Act left untouched took decades more. The 1833 Act that ended slavery across the empire still kept most freed people working as unpaid “apprentices”, and Royal Museums Greenwich notes that full emancipation came only in 1838, with no compensation for any of the formerly enslaved.