Noszlopy was born in Budapest, Hungary, where his father and grandfather were bakers. He graduated with a degree in museology (art history and subsidiary subjects) from Eötvös Loránd University in 1956. In October 1956, he was elected to the Revolutionary Committee of the Hungarian Artists' Association, but was arrested shortly after the second Soviet military intervention, the same year. He fled Hungary and lived briefly in Vienna and Paris, then settled in London.