Tonga 1962 Emancipation type 59 Complete Setting of 30 PROOF in BLACK

1962 (7 Feb) Emancipation type 59 opt PROOF in BLACK on grey vertically laid paper of the complete 5×6 setting used to overprint the upper halves of sheet of the 1d 5d to 8d and 5s values. Fold between columns 2 and 3 otherwise very fine. A remarkable item which may be unique. [For the 4d value of slightly wider format the spacing between impressions had to be increased]. Originally purchased from Stanley Gibbons (still on their card)