Grissell is the shorthand name of the firm H & M D Grissell of the Regent’s Canal Iron Works, Eagle-wharf Road, Hoxton. They cast six rectangular boxes with pyramidical roofs surmounted by an iron ball that were opened to the public in April 1855—the first letter boxes in London. They were situated in Fleet Street, the Strand, Pall Mall, Piccadilly and Rutland Gate.