In 1939 brother Andrew went to Rome to continue his education, where he enrolled at the Faculty of Philosophy of the Pontifical University of St. Thomas Aquinas, Angelicum.
In 1950 he moved to England in 1951, he worked in Australia, where, together with Archimandrite George (Bryanchaninov) founded in Melbourne a missionary center for Eastern-rite Catholics.
In 1969 Katkov was an official guest of the Moscow Patriarchate, gained respect by his Russian Orthodox episcopal hosts.
In August 1969, Bishop Katkov, at the invitation of Metropolitan Nicodemus (Rotov) visited the USSR, Moscow and other cities of Russia and Ukraine.
During a visit to the Pskov-Caves Monastery with abundant gathering of the faithful governor, in the presence of Bishop Andrei Katkov, by many years these monks proclaimed Pope Paul VI.
In the Trinity-Sergius Lavra Bishop Andrew prayed at the shrine of St. Sergius, and in Odessa met vacationing there Patriarch Alexy I (Simansky), who gave him a rosary with her hands and Panagia.
Shortly thereafter, on December 16, 1969, the then Metropolitan Alexei of Tallinn, now Patriarch Alexei II, acting as Director of Affairs of the Moscow Patriarchate, announced the Sacred Synod of the Russian Orthodox Church's decision to admit Catholics to receive communion in Russian Orthodox churches.