Table: locomotive_list_5
Columns: number_name
description
livery
owner_s
date

Question: Which owner has a description of Mark 1 pos and is dated 1956?
SQL: SELECT "owner_s" FROM locomotive_list_5 WHERE "date" = 1956 AND "description" = 'mark 1 pos'

Question: Which owner has a description of Mark 1 CK and is dated 1953?
SQL: SELECT "owner_s" FROM locomotive_list_5 WHERE "date" = 1953 AND "description" = 'mark 1 ck'