Why British motor boats attacked Kronstadt in 1919

Why did British coastal motor boats attack Russian forces at Kronstadt in August 1919?

The raid was part of Britain's intervention in the Russian Civil War in support of White Russian forces.

The August 1919 coastal-motor-boat attack on Kronstadt belonged to the Allied intervention after the First World War. British forces were broadly assisting White Russian opponents of the Bolsheviks. Participants could receive decorations for this otherwise easily overlooked campaign. The answer reserves the tactical detail but supplies the essential political setting for the raid.