After successfully being called to the English Bar in 1950, he returned to the city of Port Harcourt in the old eastern Region of Nigeria where the independence movement was growing.

Upon completion of his secondary school education at Christ the King College, Onitsha, young Ambrose successfully sat for and made distinctions in his senior Cambridge Certificate exam and was subsequently employed in the Civil Service of the then Eastern Region of Nigeria where he worked as a clerk in the judiciary of the Eastern Region government for a few years.

His working career took him to Lagos, Enugu and Port Harcourt where he served diligently as a clerk of court before proceeding to the Lincoln's Inn for his qualification as a lawyer.

On his return from England as a lawyer, he commenced his legal practice, setting up his Law firm in the oil rich city of Port Harcourt, Nigeria.

According to an oration presented by The Order Of the Knights of Saint Mulumba, KSM, Port Harcourt in honor of His Majesty the King:"We recall the crucial role he played as a Catholic in post-war Rivers state.

"His Majesty Ambrose Ezeolisa Allagoa was crowned king on the 12th of April, 1980 in succession to his father and as Mingi XI he reigned for 23 years .