Were long-range aircraft such as Liberators available for coastal convoy patrols in 1939-40?
Short answerNot in useful numbers that early; some convoy cover instead fell to aircraft such as the Swordfish because it could remain airborne for long periods.
NotesLiberators and other capable long-range patrol aircraft became important later. In 1939-40 commanders had to work with existing types, and the slow Swordfish offered valuable endurance above a convoy. The comparison shows why an apparently obsolete aircraft could remain operationally useful in a role where time on station mattered more than speed.