Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_25695027_1 (number_built VARCHAR, valve_gear VARCHAR, cylinder_size VARCHAR, firebox VARCHAR)

### Question ###
How many engines were built with a cylinder size of 20 ½” x 26”, firebox is belpaire and valve gear is from Stephenson?

### Accurate SQL ###

SELECT number_built FROM table_25695027_1 WHERE cylinder_size = "20 ½” x 26”" AND firebox = "Belpaire" AND valve_gear = "Stephenson"