British preacher Charles Spurgeon and long time friend Thomas Johnson, a former slave and first black American missionary to Africa

Very recommendable! Great story telling by Lawrence Reed!

Here we have e.g. a great white supremacist Charles Spurgeon spreading the gospel of abolitionism and who sponsored a former American slave to come to England to study at his school. (Caution: irony)

I would say besides Frederick Douglas, Booker T. Washington, and W.E.B. Dubois, Thomas Johnson should be much better known!

It is highly surprising and odd that the Wikipedia entry on Charles Spurgeon does not contain any reference to Thomas Johnson. Plus, Wikipedia does not even have an entry for Thomas Johnson (I checked e.g. the disambiguation page)

A Christmas Story From 'the Prince of Preachers' - Foundation for Economic Education Charles Spurgeon did far more than give lip service to Christmas, and his ideas were carried to the ends of the earth.

The article also refers to this book published in 2017:

Steal Away Home: Charles Spurgeon and Thomas Johnson, Unlikely Friends on the Passage to Freedom

Here is the autobiography by Thomas Johnson:

Twenty-Eight Years a Slave: or the Story of My Life in Three Continents - North America, Europe and Africa - An Autobiography