Floating anti-aircraft defenses on waterways

Were barges or hulks armed to defend British waterways from air attack?

Yes; vessels carried anti-aircraft guns, and larger offshore forts also protected approaches such as the Thames against aircraft and surface threats.

Barges and hulks could support anti-aircraft weapons where a fixed land battery was inconvenient. Larger sea forts built like offshore platforms protected the Thames approaches. Together they show how home defense extended across the boundary between land, river, and sea.