Hundreds of demonstrators from the Free Tibet Campaign, who want an end to Chinese occupation of Tibet, gathered to greet China's president, Hu Jintao.
Some of the demonstrations were more symbolic than vocal. A group of campaigners operated a radio-controlled tank carrying a Chinese flag as part of their protest.
Police were on hand to ensure that opponents and supporters of the Chinese government expressed their views peacefully.
Despite large-scale protests, large numbers of people descended on the Mall in London to wave flags and take photographs as China's president and the Queen drove past.
Hu Jintao accompanied the Queen in a carriage on his way to Buckingham Palace, where he and his wife will stay.
Hu Jintao also met Princess Anne as the first day of his visit gathered pace.
The Chinese president appeared to enjoy a warm relationship with his host, the Queen.
The president had the opportunity to met Tony Blair, as well as Foreign Secretary Jack Straw and Home Secretary Charles Clarke. He will meet Mr Blair for talks on Wednesday.
The Chinese president was given the opportunity to inspect a guard of honour in Horseguards Parade as part of the royal welcome extended to him.
The Queen and the Duke of Edinburgh presented their guests with gifts, including framed photographs of the royals and a jewellery box.