cover 1931, cover from Nairobi to Zanzibar, bearing Kenya and Uganda 1c. tied by Nairobi c.d.s. and Zanzibar 1927-30 Postage Due 3c. and 1930-33 Postage Due 6c. vertical pair all with Zanzibar c.d.s.; rare. S.G. D3, D21, £72 off cover