Prince Edward Island SG 14, 23 Mint 1862-69 3d blue block of 4 with compound perfs

1862-69 3d blue on yellowish toned paper, block of 4 from right of sheet, plated as R5-6/4-5 (= lower corner), perf compound of 11 (at right and foot) and 11½-12, brilliant o.g. (lower pair unmounted). A wonderful and very rare multiple, demonstrating the occasional use of the perf 11 machine at the sheet margins, and comprising three different variants of the compound perf (SG 23) se-tenant with a normal (SG 14) at upper left. [R5/5 11 is perf at right, R6/5 perf 11 at right and foot, R6/4 perf 11 at foot]. Unquestionably the finest compound perf multiple (any value !) we have ever handled, with even fine singles very scarce, and in exceptional condition. RPS cert (1973). - P267001769