Career
He emigrated to England in 1882 and became a naturalized British citizen in 1887. Giwelb was noted for his genial and unassuming nature which contrasted with the rarity of the material in which he dealt. Giwelb was responsible for the unmasking of the forger Doctor Bernhardt Assmus, after he bought forged Penny Black VR official stamps from Assmus.
He accompanied the police on a visit to Assmus" premises at 12 Church Street, Islington, and assisted them at Vine Street Police Station in sorting the seized material.