These stamps were used to pay both postage and revenue fees. In the latter case the companies using them often overprinted the stamps with their name or initials. I suspect that this is the case here, especially since the stamp has a manuscript cancel, not a postal cancel. Manuscript cancels were very common when a stamp was used for revenue purposes.
Very good. Early registered posts in India were canceled with both manuscript and hand black stamp. The revenue which was used in the post office was canceled with hand black stamp only. This trend continues even today. In Bangladesh, saving stamps are canceled with a hand black stamp at the post office.
This stamp has been used on a receipt, I think. The letters SRDC must stand for S— R— District Council, a local authority somewhere in the UK. I’m not sure what place name the SR might stand for. Local councils often overprinted their stamps for this purpose, I suppose to prevent theft or misuse.
