Patent Seal, Image & Found by DetectingDavid.
Found in Essex, 33mm.
"The large lead seal has the word PATENT around the edge."
Unfortunately most of the face has delaminated away but there is an continuous circular border line with the following letters curved outside it, --TTS'S PATENT Inside is another continuous circle of alternate wedge shapes that bounds a device that is largely missing.
Possibly a cloth seal.