What happened to the household slaves in Britain as the Romans were leaving?

Now there's a million dollar question - what happened to the slaves.  The Romans didn't leave Britain though, the Roman army did.  By this point the Roman army was mostly made up of recruits from near the borders of their empire including outside their own borders.  The Romans like to keep potential enemy young men busy by offering them a job in the army and then moving them away from their home territory.  The history of the various legions is interesting.  They really got around.  Anyway, the Roman army left Britain in an organised demobilisation. They took everything and everyone part of the army.

By the time the Romans left Britain south of Hadrian's Wall had become Romano-British, or 400 years the local flavour of Roman.  That's a lot of generations.  What were your family doing in the 1600s?  The people stayed behind.  

When I was at school we were taught that the Angles, Saxons, and Jutes who hardly ever get mentioned, simply swept in and swept everyone left behind away, except for Wales.  The Welsh are still here, they were the Romano-British at the point where the military left.  It's always more complicated though.

Landscape regression studies and place-name evidence shows that it wasn't a clean sweep.  The economy collapsed, people moved into the countryside.  In the north and west Romano-British kingdoms formed.  They politicked, squabbled, and intermarried with the new Germanic Kingdoms for a few hundred years until they were swallowed up.  During this period little kingdoms got eaten up until something large enough to begin to form states again began to emerge.

All these societies used slaves.  There were still slaves around when the Normans conquered England, they're itemised in the Doomsday Book.  There were no more slaves and no more serfs after the Black Plague.  Society was completely shaken up and needed able bodies who were able to set their own terms.  It wasn't like American plantations though, slaves were always relatively few in number and tended to be household retainers and servants.  At least after the proper Roman period when agricultural slaves were converted into serfs.