Question: who plays chummy's mother on call the midwife
[{'answer': 'Cheryl Campbell', 'provenance': [{'wikipedia_id': '49808705', 'title': 'List of Call the Midwife characters', 'start_paragraph_id': 100, 'start_character': 12, 'end_paragraph_id': 100, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::Previous recurring characters.\n'}]}]