Question: when was the tower of london last 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': 0.9904073966945661, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6177370707121389797}, 'section': 'Section::::Abstract.'}]}]