Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_1569516_1 (platform VARCHAR, operator VARCHAR, service_pattern VARCHAR)
### Question:
How many platforms have a southern opertator and the pattern is all stations via clapham junction?
### Answer:
SELECT COUNT(platform) FROM table_1569516_1 WHERE operator = "Southern" AND service_pattern = "All stations via Clapham Junction"