The Phelps family pickets mourners across the country, to mark what it describes as God's revenge on the US for tolerating homosexuality.

Their actions are in the name of the Westboro Baptist Church, which numbers 71 and is headed by "Gramps", preacher Fred Phelps. The church, which is based in Topeka, Kansas, mostly comprises his extended family.

Louis Theroux, himself no stranger to people with unconventional views, says the Phelpses are the most extreme people he has ever met. But in the following interview, he reveals how three weeks with them left him perplexed by their motivation.