The first ever watermark to appear on the British stamp is the “Elephant’s Head”. The elephant continues to appear on the stamps of “East India Company”. This new set of stamps issued between 1865 and 1876 bore a portrait of Queen Victoria in an oval vignette inside a rectangular frame. Altogether, some 24 stamps (ONLY) were issued, all of which were watermarked by the Elephant’s Head.

East India stamps were issued from the 1850s to 1873 only because the Company was dissolved in 1874. Thereafter, the stamps were issued by "India Postage".  ie. from Scott# 33 onwards, the stamps were issued by the India Postage of the Empire government.

From Google as below:

The East India Company (EIC)^[a] was an English, and later British, joint-stock company founded in 1600 and dissolved in 1874.^[4] It was formed to trade in the Indian Ocean region, initially with the East Indies (the Indian subcontinent and Southeast Asia), and later with East Asia. The company seized control of large parts of the Indian subcontinent and colonised parts of Southeast Asia including Hong Kong and Singapore. At its peak, the company was the largest corporation in the world by various measures. The EIC had its own armed forces in the form of the company's three Presidency armies, totalling about 260,000 soldiers, twice the size of the British army at the time.^[5][6] The operations of the company had a profound effect on the global balance of trade.

不列顛東印度公司（英語：British East India Company，縮寫：EIC，通稱英國東印度公司^[1]，別名「約翰公司」（John Company），是一個特許公司。西元1600年12月31日，英格蘭女王伊麗莎白一世授予該公司皇家特許狀，給予它在印度貿易的特權而組成。它於東印度貿易的壟斷權達兩個世紀。隨時間的變遷，東印度公司從一個商業貿易企業變成印度的實際主宰者。在1858年被解除行政權力為止前，它還獲得了協助統治和軍事職能.

You will get it exactly as the above scans.

I combine shipping.