One of the world's richest monarchs, the Emir of Qatar, will begin a state visit to Britain later on Tuesday when he meets the Queen in Windsor.
Sheikh Hamad bin Khalifa Al-Thani will be met by the British monarch and Duke of Edinburgh ahead of a horse-drawn carriage procession to Windsor Castle.
A sovereign escort of the Household Cavalry will escort the procession, and Army personnel will line the route.
The government hopes the three-day visit will benefit UK businesses.
More than 90 flagpoles will be installed along the route of the procession, decorated with both the Union and Qatari flags.
BBC diplomatic correspondent, James Robbins, says state visits are very much an instrument of government policy.
He says improving relations with the energy-rich Gulf States is a top priority for the government, which invited the emir to Windsor in June, a month after the general election.
The government hopes the visit will bring more of the huge oil and gas wealth of the Gulf State to British firms, and secure vital energy supplies.
The emir, who arrived on Monday ahead of the formal state visit, is a powerful figure in the Gulf region and considered one of its more progressive rulers.
Qatar helped rescue Britain from energy shortages during last winter's exceptional cold by supplying more than 10% of the country's gas needs.
Qatar invested more than £2bn in Britain last year, and ministers hope the country's vast wealth could help an export-led recovery.
RAF operations in Qatar are also crucial to the military supply line for Afghanistan.