Name the number of going to for  thurlby, braceborough spa at departure being 16.50
CREATE TABLE "table1_17200372_2" (
  "departure" text,
  "going_to" text,
  "calling_at" text,
  "arrival" text,
  "operator" text
);
SELECT COUNT("going_to") FROM "table1_17200372_2" WHERE "calling_at"='Thurlby, Braceborough Spa' AND "departure"='16.50';