Most W. African so called Pidgin English are secondary creole languages derived from Cabo Verde Crioulo. Crioulo was invented by the first generation of children (pikin) born in the island of Santiago by 1460 and became the mother language and the working and trading and praying language of the newly born Cabo Verde nation irrespective of skin colour, religion and social position. The lexikon of crioulo is 95% Portuguese, the grammar is neither Portuguese nor African it was invented by pikin. Only a small minority of children went to school to become priests and learned Portuguese. The inhabitants of Santiago received as a concession from the king of Portugal the monopoly of commerce with the African coast from river Sanaga (Senegal) to Serra Leoa, where thunders where roaring. The Bishop of Cabo Verde was in charge of the same West African coast. Cabo Verde was thus a success story of economic development. While speaking Crioulo they planted cotton, sugar cane and vine as cash crops, manufactured sugar and coloured cotton textile and bred horses among other things. They settled in the W. African coast to exchange their goods, to catechise and taught crioulo around them. Crioulo became the lingua franca like hausa today. By 1600 English people settled in Sierra Leone and brought with them Irish slaves and stayed until 1965. Crioulo was gradually relexified in English, adopted some Yoruba vocabulary and became Krio, which is nowadays spoken by 100% Sierra-leonians. At different dates Sierra-leonians speaking Krio where taken by English sailors, army officers and merchants as far as Ghana, Nigeria, Fernando Po and Cameroon where they taught Krio, as well as Jamaica where they served in the army and South Carolina, where they cultivated rice and manufactured baskets. Your question goes far back in history and has no simple answear. Up to you to investigate how your Nigerian creole developed from Krio keeping a few residual Portuguese words. For eventual further information, please, use my address soushort.joyc@mail.telepac.pt.