What is the highest BR number with a SECR number of 765?
CREATE TABLE "l_class_locomotive_fleet_summary" (
  "secr_no" real,
  "sr_no" real,
  "br_no" real,
  "builder" text,
  "date_delivered" text,
  "date_withdrawn" text
);
SELECT MAX("br_no") FROM "l_class_locomotive_fleet_summary" WHERE "secr_no"=765;