In 'Spycatcher' IIRC MI5 actually steamed letters open with a kettle, or rolled them out of the gap at the top of the flap with a split cane! They had no way (a

In 'Spycatcher' IIRC MI5 actually steamed letters open with a kettle, or rolled them out of the gap at the top of the flap with a split cane! They had no way (at that time) to deal with cellotape, however. I suspect the metadata is a pretty valuable resource in itself. Suggests that people wishing to protect their privacy would do well to shield the inside of their envelopes with junk text, tape them shut, post them from random locations and use mail forwarding services and a mailbox service