Question: where does the river thames stop being tidal
[{'answer': 'Teddington Lock', 'provenance': [{'wikipedia_id': '49031', 'title': 'River Thames', 'start_paragraph_id': 2, 'start_character': 189, 'end_paragraph_id': 2, 'end_character': 204, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '49031', 'title': 'River Thames', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 348, 'bleu_score': 0.539969687525176, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3581088030326903678}, 'section': 'Section::::Abstract.'}]}]