Question: What is the fleet size of the Vanguard 0-6-0DH class?
SQL: SELECT "Fleet Size" FROM "2-12085438-1" WHERE "Class" = 'Vanguard 0-6-0DH';

Question: What is the year of introduction for the Electro-diesel locomotive?
SQL: SELECT "Introduced" FROM "2-12085438-1" WHERE "Type" = 'Electro-diesel locomotive';

Question: What is the average fleet size for the Shunter type introduced in 1959?
SQL: SELECT AVG("Fleet Size") FROM "2-12085438-1" WHERE "Type" = 'Shunter' AND "Introduced" = '1959';

Question: What is the smallest fleet size with a type of Shunter introduced in 1953?
SQL: SELECT MIN("Fleet Size") FROM "2-12085438-1" WHERE "Type" = 'Shunter' AND "Introduced" = '1953';