Question: who was the only ruler of britain who ruled instead of a king or queen
[{'answer': 'Oliver Cromwell', 'provenance': [{'wikipedia_id': '47063', 'title': 'Monarchy of the United Kingdom', 'start_paragraph_id': 51, 'start_character': 347, 'end_paragraph_id': 51, 'end_character': 362, 'bleu_score': 1.0, 'section': 'Section::::History.:Personal union and republican phase.\n'}]}, {'provenance': [{'wikipedia_id': '47063', 'title': 'Monarchy of the United Kingdom', 'start_paragraph_id': 51, 'start_character': 0, 'end_paragraph_id': 51, 'end_character': 892, 'bleu_score': 0.9867102250666441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6005164695466567933}, 'section': 'Section::::History.:Personal union and republican phase.\n'}]}]