The message .com
from "Staffbull" contains these words:

What is the best way to anchor these down as the
biggest security issue would be for someone just to lift it up !!

Stakes into the ground. I'd use a bit of angle-iron with a hole in it,
driven well in then bolt through the hole to the frame of the shed.

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Skipweasel
Pay no attention to that man behind the curtain.