Just heard a piece about this on the radio this morning.
While the slave trade was abolished in 1807, slave ownership continued for some years - and then the owners got compensation for the value of their slaves when they were finally freed. The compensation led to a bureaucracy and record-keeping. All of this and loads of info is available on the
http://www.ucl.ac.uk/lbs/ website of the University College London project. Searchable for the owners, but not for the slaves. You could spend days following up the info here: as the website says,
Colonial slavery shaped modern Britain and we all still live with its legacies. The slave-owners were one very important means by which the fruits of slavery were transmitted to metropolitan Britain. We believe that research and analysis of this group are key to understanding the extent and the limits of slavery's role in shaping British history and leaving lasting legacies that reach into the present. The stories of enslaved men and women, however, are no less important than those of slave-owners, and we hope that the encyclopaedia produced in the first phase of the project, while at present primarily a resource for studying slave-owners, will also provide information of value to those researching enslaved people.