London, England and England have had a very extensive history. See the picture of William Tyndale below who translated the Bible into English.
The colonies were populated with Christians from England laying the foundation for the founding of the United States.
Statistics from 2011:
The largest religion in the 2011 Census for England and Wales was Christianity with 33.2 million people (59.3 per cent of the population). Muslims were the next largest religious group with 2.7 million people (4.8 per cent of the population).
The grand and divine opportunity of preaching the Gospel in London for 10 days is in part awakening the historical roots of Christianity that effected the US and the world.