Question: when did the uk stop using the gold standard
[{'answer': 'September 19 , 1931', 'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 49, 'start_character': 256, 'end_paragraph_id': 49, 'end_character': 275, 'bleu_score': 1.0, 'section': 'Section::::Abandonment of the gold standard.\n'}]}, {'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 49, 'start_character': 0, 'end_paragraph_id': 49, 'end_character': 708, 'bleu_score': 0.9513840121740441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15327192559328999967}, 'section': 'Section::::Abandonment of the gold standard.\n'}]}]