Question: british colonial rule in west africa started in the year
[{'answer': '1821', 'provenance': [{'wikipedia_id': '2818945', 'title': 'British West Africa', 'start_paragraph_id': 3, 'start_character': 240, 'end_paragraph_id': 3, 'end_character': 244, 'bleu_score': 1.0, 'section': 'Section::::Historical jurisdiction.\n'}]}, {'provenance': [{'wikipedia_id': '2818945', 'title': 'British West Africa', 'start_paragraph_id': 3, 'start_character': 123, 'end_paragraph_id': 3, 'end_character': 525, 'bleu_score': 0.8080868719114711, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12829932953794804094}, 'section': 'Section::::Historical jurisdiction.\n'}]}]