Question: when did pound notes stop being legal tender
[{'answer': '11 March 1988', 'provenance': [{'wikipedia_id': '50389230', 'title': 'Bank of England £1 note', 'start_paragraph_id': 6, 'start_character': 1145, 'end_paragraph_id': 6, 'end_character': 1158, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '50389230', 'title': 'Bank of England £1 note', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 1520, 'bleu_score': 0.9926872630878321, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 105002268030560081}, 'section': 'Section::::History.\n'}]}]