"In 1847, Henry Archer constructed the first (rouletting) machine, the "Archer Roulette", to separate stamps. His plan, submitted to the Postmaster General on 1 October, 1847, was referred to the departments of the General Post Office and the Inland Revenue. Two such machines were built. After experimentation both machines proved to be failures. From one machine a few stamps from Plates 70 and 71 have survived. This machine consisted of lancet-shaped blades working on a fly-press principle and piercing the paper with a series of cuts.

Archer then abandoned this approach in favour of perforation, a process which used rows of small round pins to punch out the holes. In 1848 Archer patented his perforation machine which worked on the "stroke" principle. The arrangement of the pins enabled the top and sides of each stamp across the row to be perforated in a single operation, and this became known as "comb" perforation. Perforation trials were conducted in 1849 and 1850 under the auspices of the British Government and stamps from these trials were first issued towards the end of 1850. The Archer machine proved the viability of the process but never entered service. Archer's patent for his perforating machine (no. 12,340 of 1848, dated May 23, 1849) was purchased for £4,000 in June 1853. New machines based on Archer's principles were constructed by David Napier and Son Ltd; these were initially used in October 1853 for revenue stamps and from January 1854 for postage stamps."

""Misperforated" means a stamp has perforations, but they are so poorly aligned with the design that they constitute a production freak. The line between "poorly centered" and "misperforated" is somewhat a matter of personal judgment."