The British government was an early convert to the benefits of long-distance telegraphy. In 1857, during the Indian Mutiny, an emergency request for troops had taken 40 days to reach London from Lucknow. The following year, with the Mutiny effectively over, the government managed to get a message through the short-lived 1858 transatlantic cable, cancelling an embarkation order to troops in Canada and saving an estimated 50,000 pounds.
The first London-to-India telegraph link was opened in 1864. This ran overland through Europe to the Musandam Peninsula at the top of the Persian Gulf, then on to India via undersea cable. Unfortunately, problems with the overland section - it was prone to attacks by the locals - limited its usefulness, forcing the government to invest in a new link between Britain and India. This was all undersea, apart from a relatively short length across Egypt.
The last section of this new cable, laid by the Falmouth, Gibraltar and Malta Telegraph Company, was brought ashore at Porthcurno on 8 June 1870. As the name suggests, the original intention was to bring the cable ashore at Falmouth, but late in the planning stage it was decided that the risk from ships' anchors in that area was too great, prompting the switch to Porthcurno.
Watching the landing of this cable was the one-time Manchester cotton merchant John Pender, who had been a director of the Atlantic Telegraph Company, responsible for the 1858 transatlantic cable. Four separate companies had been involved in laying the 1870 London-India cable, and in 1872, under Pender's chairmanship, they were all merged to form the Eastern Telegraph Company.
Picture courtesy of Engineering and Technology Magazine
The Story of Cable and Wireless Article