The zero historical connection argument applies with equal force to every group of relatively recent immigrants to Britain from nations with no involvement in the Atlantic slave trade. Polish families who came to Britain in the 1940s and 1950s, Vietnamese families who came in the 1970s and 1980s, Somali families who came in the 1990s and 2000s: all of these communities are now British and would be subject to a general reparations levy. None of them has any historical connection to the Atlantic slave trade.
The reparations campaign has no answer to this. It cannot explain why a Vietnamese-heritage British citizen should contribute to a payment for a colonial wrong their ancestors had nothing to do with, except to say that they are now British and therefore share in Britain’s obligations. But that argument proves too much. It would make every naturalised British citizen retroactively responsible for every historical wrong Britain has ever committed, regardless of where they came from or when they arrived.