law: The Joint-stock Companies Act, 1857
  Legal Instruments of Company
  XLV. Contracts how made.-
  Contracts on behalf of any Company registered under this Act may be made as follows; (that is to say)
  (1) Any contract which, if made between private persons, would be by law required to be in writing, and if made according to English law to be under seal, may be made on behalf of the Company in writing under the common seal of the Company; and such contract may be in the same manner varied or discharged.
  (2) Any contract which, if made between private persons, would be by law required to be in writing and signed by the parties to be charged therewith, may be made on behalf of the Company in writing signed by any person acting under the express or implied authority of the Company; and such contract may in the same manner be varied or discharged.
  (3) Any contract which, if made between private persons, would by law be valid although made verbally only and not reduced into writing, may be made verbally on behalf of the Company by any person acting under the express or implied authority of the Company; and such contract may in the same way be varied or discharged. And all contracts made according to the provisions herein contained shall be effectual in law, and shall be binding upon the Company and their successors, and all other parties thereto, their heirs, Executors, Administrators, or representatives, as the case may be.