According to Wikipedia
[043] this photograph illustrates ;
'At Scapa Flow, a Royal Navy net laying vessel prepares to lay an anti-submarine net, which is 900 feet (275 metres) long, weighs over 40 Imperial tons (41 tonnes) and could be laid in 4 minutes.' This was probably either H.M.S. Guardian or her sister H.M.S. Protector built in 1936. The photograph taken by Hampton, J A (Lt),, Royal Navy official photographer, is borrowed with thanks to the WWII collection of the Imperial War Museum.
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