Following World War II, he left for Britain to specialize in surgery at the Royal College of Surgeons.

He was invited as a guest to the ceremonial opening of Parliament that marked the start of self-rule in Ceylon on February 4, 1948.

After he returned to Ceylon, he was appointed Consultant Visiting Surgeon at the Colombo General Hospital in 1947 and served in that capacity until he retired on 21 January 1971.

During his 70 years as a doctor, he has performed nearly a hundred thousand surgical operations, including one on the fatally wounded Prime Minister S.W.R.D.

Carlo Fonseka had provided a short review of Anthonis's professional career in the Ceylon Medical Journal.