The head of Russia's Orthodox Church begins a four-day visit to Britain on October 15 that includes an audience with Queen Elizabeth II.
But the visit of Patriarch Kirill has provoked some resistance because of his strong support for Russian President Vladimir Putin.
Patriarch Kirill is set to be in London to celebrate the 300th anniversary of the establishment of the Russian Orthodox Church in Britain. The main purpose of the trip is to meet with his congregation, but he also will visit with Archbishop of Canterbury Justin Welby and see the queen at Buckingham Palace.
The visit will make Kirill the first Russian Orthodox Church patriarch to visit Britain. He will hold a number of prayer services and blessings at various Russian Orthodox sites.
The audience with the queen is being questioned, especially in light of British Foreign Secretary Boris Johnson's charge this week that Russia risks becoming a "pariah nation" because of its aggression in Syria and Ukraine.
Critics are concerned that Kirill's meeting with the queen will be used to boost Putin in Russia. Labour Party lawmaker Alison McGovern said it is wrong to give "a PR opportunity to one of President Putin's key allies."