One thousand years ago, when slavery was an accepted part of Anglo-Saxon life, Bristol's merchants were selling enslaved white people to Viking settlers in Ireland. A shortage of labour in Ireland meant that there was a ready market for workers. Some of the poorest accepted slavery voluntarily, hoping for a better life as a farm worker or house servant in Ireland. Some were prisoners of war. Sometimes a family sold a child to avoid starvation. But merchants would also kidnap beggars, orphans or someone who was just in the wrong place at the wrong time, to supply the demand.

Very little was done against this trade. The king taxed the sales of the enslaved, so had no reason to act against it. Bishop Wulfstan of Worcester, who died in 1095, did preach against the Bristol merchants who traded in people. The monk William of Malmesbury wrote the life story of Wulfstan in about 1130: he described how Wulfstan had campaigned against the slave trade from Bristol. This 'ancient custom' was banned by law in 1102.

Bristol's merchants were known for their part in the different slave trades. Bishop Wulfstan spoke out against the trade in enslaved people from England to Ireland through Bristol. Judge Jefferies in 1685 raged at the Mayor and Councillors for their involvement in buying criminals and rebel prisoners to sell to the plantations in Barbados. From the late 1700s, Bristol merchants were campaigning to get a share of the profitable transatlantic slave trade.