Question: who was the lead singer of the bay city rollers
[{'answer': 'Les McKeown', 'provenance': [{'wikipedia_id': '30508', 'title': 'Bay City Rollers', 'start_paragraph_id': 2, 'start_character': 158, 'end_paragraph_id': 2, 'end_character': 169, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]