The construction of large-scale public railways, linking London to many of the major cities, transformed London's social and business life. The underground network and tramways followed. The growth of shipping and, in particular, the construction of the famous clippers enabled tea to be transported from China to the Thames. The transport links were crucial in the extending of colonial domination and international trade. Industrial progress was sometimes double-edged. The invention of the modern water closet resulted in the piping of raw sewage into the Thames, which at the time was the source of London's water supply. In 1833, 10,000 Londoners died in a cholera epidemic, which led to a law banning burials within the city boundaries. 18th century legislators, faced with widespread poverty and crime, had responded by creating more and more capital felonies. Sir Robert Peel, as Tory Home Secretary, decided on a more enlightened approach, creating the Metropolitan Police Force in 1829. He was then able to push forward many law reforms. Later, as President of the Board of Trade, he was instrumental in removing unnecessary tariffs and moved towards free trade, which further increased prosperity. William Gladstone, who presided over four Ministries in the latter half of the century, was also a Liberal, a democrat, reformer and an advocate of free trade. Benjamin Disraeli, a Tory Prime Minister, and a favourite of Queen Victoria, also sought political reform and to increase enfranchisement of the working classes. The great reformers of the 19th century were faced with unprecedented social problems thrown up by the changes which followed the Industrial Revolution.