Great Britain 1840 1d Rainbow trial (State 2), SGDP20Great Britain 1840 1d Rainbow trial (State 2), SGDP20. A very fine unused four margin imperforate example printed in deep red brown on thin white wove paper, showing "Tiny dash" in S. E. corner square indicative of state two. A scarce specialised philatelic item of early GB postal history. These trials were produced to test various combinations of stamp and cancellation ink. It has long been considered that the voiding of the corners was achieved by