CREATE TABLE table_21819 ("SECR No." FLOAT, "SR No." FLOAT, "BR No." FLOAT, "Builder" TEXT, "Date Delivered" TEXT, "Date Withdrawn" TEXT)

What is the withdraw date for secr no. 771?
SELECT "Date Withdrawn" FROM table_21819 WHERE "SECR No." = '771'
SELECT "Date Withdrawn" FROM "table_21819" WHERE "SECR No." = '771'