Banque du Congo Belge/Banque Centrale du Congo Belge et du Rwanda-Urundi, watermarked papers for 5, 10, 50, 1000 and 5000 Franc notes, as used on almost all Belgian Congo notes printed in the UK between 1941 and 1959, glued into individual blue card frames, annotations on paper, as produced, very rare (5 papers)
BNB B203, B211-B315, Pick 8, 14-35 for range of types £200-£260

Regardless of the design and date of the note, the same watermarked paper was generally used for each denomination, with the exception of the 5 Franc paper, which was used only on the 1924-30 issue (later 5 Franc notes had no watermark).