Malta is a self governing dependency of the Kingdom of Great Britain, unlike the Isle of Man and the Channel Islands it is not dependent on the Crown but rather developed it's own relationship with Great Britain sui generis.
The Maltese Government acts an almost entirely independent entity within the Kingdom setting their own economic and immigration policies but defense and foreign affairs are left to the Government of Great Britain to decide.
On top of this Great Britain operates a military and naval base in Malta as a second base of operations for its Atlantic and Mediterranean fleets.
This arrangement came about in 1960 when the Crown Colony of Malta was given a referendum on its continued relationship with Britain. It had three options 2 were to become independent either as a republic leaving the Imperial Federation, a constitutional monarchy with Mary III as its head remains g in the Imperial Federation or it could remain entirely under the protection of Britain as a state in Free Association with Great Britain responsible for defence and representing Malta's interests abroad.