Table: railway_rolling_stock
Columns: year
rr_class
rr_nos
builder
builder_nos
gwr_br_nos

Question: Name the builder numbers with RR class of a1 and year less than 1916
SQL: SELECT "builder_nos" FROM railway_rolling_stock WHERE "rr_class" = 'a1' AND "year" < 1916

Question: Name the RR numbers of hudswell clarke and years before 1914
SQL: SELECT "rr_nos" FROM railway_rolling_stock WHERE "builder" = 'hudswell clarke' AND "year" < 1914