The John Wilks British East Africa: 1897 'On Zanzibar' Overprints: Original Trial Overprint, 1a. indigo and red overprinted in red, block of four with gum, minor imperfections. Ex Vestey. The red overprint was rejected in favour of the black and it is thought that a single sheet of sixty was produced. This is one of only two recorded blocks of four. Photo. (Image1)

The John Wilks British East Africa: 1897 'On Zanzibar' Overprints: 41/2a. orange and red, variety no serif to left-hand "4" [R. 1/1], mint, fine. S.G. 83a, cat. £1,400. Photo. (Image1)

The John Wilks British East Africa: 1897 'On Zanzibar' Overprints: 41/2a. orange and red, variety no serif to left-hand "4" [R. 1/1], used, fine. S.G. 83a, cat. £850. Photo. (Image1)