Question: who is the longest running character in coronation street
[{'answer': 'Ken Barlow', 'provenance': [{'wikipedia_id': '6851', 'title': 'Coronation Street', 'start_paragraph_id': 8, 'start_character': 41, 'end_paragraph_id': 8, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::History.:1960s.\n'}]}, {'provenance': [{'wikipedia_id': '6851', 'title': 'Coronation Street', 'start_paragraph_id': 58, 'start_character': 0, 'end_paragraph_id': 58, 'end_character': 888, 'bleu_score': 0.9626201417602621, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11940673277196913244}, 'section': 'Section::::Characters.\n'}]}]