There's a very relevant article by Tony Benn circulating. I particularly like the final sentence of this:

Now, Wilberforce was a very interesting man. He was a Conservative, he supported Pitt, he voted for the Combination Act which made it a criminal offence for more than three people to get together to call for a trade union or political reform, and then he became a Christian and he was stirred by the injustice of it and campaigned, and that’s what we’re celebrating this year, the abolition of the slave trade. And, might I add, not the abolition of slavery, don’t think that Wilberforce brought about the abolition of slavery but only the slave trade.