The first commercial overprints were applied to the 1d Draft stamp issued in March 1855 and the large format Foreign Bill stamp released in the same year.
The Draft stamp was a dual-purpose issue for both Drafts (any documents requiring payment on demand, such as cheques) and Receipts. Overprinted Draft stamps are very scarce and I am aware of just 7 different overprints on this issue. In 1860 the 1d Draft stamps were replaced by the 1d Inland Revenue stamps and the practice of overprinting became more common.
Foreign Bills were essentially bank drafts for transfer of money to a foreign country and the 1853 Stamp Act required tax to be paid by means of a special adhesive. A small number of banks and stockbroking companies overprinted the 1855 Foreign Bill stamps.