I can add another manufacturer of English Riveted Leg Irons to the list.
From the images below, by combining what is legible on the 2 different stamps, one on each basil, Laycock made these as part of an English Government contract (M&C 1865) for Military and Civilian use in 1865. My best guess is that Laycock were J. Laycock and Co, of Winlaton, England.
As the last Australian convicts were transported here from England in 1868 to Western Australia, these fall just inside the convict era. At 7 pounds in weight, these are the standard light leg irons, as opposed to heavier punishment irons, or double irons.
A convict sentenced to say 3 years on a road gang in irons would have worn these non stop for his entire sentence unless a doctor recommended otherwise. The last image is from an index to letters from the Convict Prison Hulk (Ship)"Success" to the Inspector General of Penal Establishments in Melbourne, John Price, recommending a downgrade from punishment irons to the 7lb irons. Among these letters are orders for new irons and rivets, and repairs being sent to Pentridge Prison where there must have been a workshop. John Price was later murdered by a prison gang who worked at a quarry on shore during the day.