Cloth Seal, Cloth Worker's Personal Seal, Heraldic Device, Fleur-de-Lis, CF, Image & Found by London Mudlark.
Found on the Thames Foreshore
Border of pellets containing CF above a shield bearing a single Fleur-de-Lis // double rivet
CF is likely to be the cloth workers initials - for similar seals see Nos.260, Fig.34, Egan, Lead Cloth Seals and Related Items in the British Museum, Occasional Paper 93.