[Question] Anyone has a reference for “It’s estimated that abolition cost Britain 2% of its GDP for 50 years”?

In today’s 80.000h newsletter, there is a short overview of MacAskill’s new book about longtermism. It explains that Will makes the case that is some few particular people (Quakers) started the antislavery movement. If they would have died at the wrong time, maybe the antislavery movement would not have happened. And part of the basis for this assertion is that “it’s estimated that abolition cost Britain 2% of its GDP for 50 years”.

Some time ago I’ve read that a very big factor (probably the crucial factor) for why slavery was abolished is because of energy: we learned how to use the energy in coal, which made a huge amount of work types extremely cheap if you could afford to buy a steam engine. It made work so cheap that it was cheaper than slaves, which need to be fed and sheltered, and only work for so many hours/​day, so they were not that needed anyway.

These two narratives do not seem to fit together. Of course, steam engines cannot do all kinds of work, so slaves could have still come handy in many aspects. Is it this “loss” what this 2% accounts for?

No answers.