"Lubwa's" refers to a place - either Lubwa's Fort or Lubwa's Village.
Catalogues describe these as "type-set by Revd. F. Rowling". It would appear that he probably designed and produced the stamps himself, and I would guess that he used type belonging to the Missionary Society or to a local printer if there was one.
It was sold in our 7 May 2007 auction with the following description;
272 Uganda; Cinderella; 1896-98 piece of document (writing on reverse) with four of the
manuscript overprints on 1896 postage stamps. Two of 1r at top, two of 5r below, each
stamp with black "Consular" written diagonally in black ink, the upper-left stamp with
extra mark at top ("momr" ?). Black handstamp cancel at centre of four stamps "BRITISH
VICE-CONSUL/IN THE UGANDA PROTECORATE/AND THE ADJOINING TERRITORIES". A little
discoloured or toned but a highly scarce item. Barefoot nos. 2, 3, cat.£900. : .. £150. Sold at £350 + 10%