Historically, before North Borneo joined the Universal Postal Union (U.P.U) in 1st January 1891, its postage stamps were only valid to far as Labuan, Singapore and Hong Kong. Letters going beyond these countries had to be franked with either Labuan, Straits Settlement or Hong Kong stamps, which at that time were available in Sandakan, Gaya and Kudat post offices. As Jesselton was only opened as a new settlement after the burning of Gaya in 1897, I find the Jesselton cancels both on the Perak stamps (SG19a,1891) and on the St. Settlement stamp (SG104, 1892) to be very unusual if genuine. There is no doubt, however, that the blue-ink Sandakan double ring cds may be genuine...