Question: when did the tower of london stop being used as a prison
[{'answer': '1952', 'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 1, 'start_character': 682, 'end_paragraph_id': 1, 'end_character': 686, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '31165', 'title': 'Tower of London', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1156, 'bleu_score': 0.9737023825578871, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3433965617975331525}, 'section': 'Section::::Abstract.'}]}]