I recently picked up this, John Clark & Co.'s penny token, 1854. Same size and weight as a pre-1860 copper penny.
What I find surprising about this issue is the "PAYABLE AT JOHN CLARK & CO" legend - this was presumably still illegal as of 1854 under the 1818 act banning private coinage ? In any case, this piece is rather rare, so perhaps it was not issued in enough quantity for anyone to care particularly about it. The "Professor Holloway" issue of 1857 and 1858 was much larger in quantity, and saw circulation in London, but had no indication that it was a payable token.