Falkland Islands 1891 SG 8a 2 1/2d rate bisect cover to UK Cat 4000 pounds

1891 envelope to London bearing horizontal strip of three 1d brownish claret from the foot of the sheet the left stamp bisected diagonally and tied by bold strikes of cork cancel. Part despatch strike on front London arrival (MY 23) on reverse. Backflap missing but clean and attractive item F7 in the Barton listing.