Princess Kate, Queen Camilla, Melania Trump in awkward moment as royals greet Donald Trump at Windsor Castle

Princess Kate has been given a reminder of the royal pecking order after an awkward moment between her and Queen Camilla greeting Melania Trump was caught on camera.

US President Donald Trump and First Lady Melania arrived on the grounds of Windsor Castle to all the pomp and ceremony afforded for a major state visit, before walking from the Marine One chopper with Prince William and Princess Kate, to meet King Charles and Queen Camilla at the front entrance to Victoria House.

Soon after the formal introductions, which included private secretaries Sir Clive Alderton and Sophie Densham, Mr Trump and King Charles began a conversation, leaving Camilla and Melania to engage in a brief chat together.

As Princess Kate and Melania engaged in conversation, Queen Camilla appeared to feel a bit left out and began to look around, before deciding it was time for Kate to head off and motioned for her to move away with her hand.

Princess Kate took the advice and obliged, quickly offering her farewells to Melania and heading back to her husband Prince William’s side.

Queen Camilla and Melania then continued their conversation as the horse-drawn carriages arrived to transport them all to Windsor Castle.

The Scottish State Coach was the mode of transport for Queen Camilla and the First Lady as they continued their catch-up.

King Charles and President Trump led the procession in the Irish State Coach, while the Prince and Princess of Wales rode in the Semi-State Landau with Warren Stephens, the US ambassador to the UK, and his wife.

Mr Trump and his wife have been treated to the full array of British pageantry, with the US President singing the praises of his nation’s close ally.

“The bond of kinship and identity between America and the United Kingdom is priceless and eternal. It’s irreplaceable and unbreakable,” Mr Trump said in a speech during a lavish evening banquet at Windsor Castle.

Referring to the so-called special relationship between the two nations, Mr Trump said: “Seen from American eyes, the word special does not begin to do it justice.”

Britain has rolled out the royal red carpet, giving Mr Trump the largest military ceremonial welcome for a state visit in living memory.

The president made little secret of his delight at being not just the first US leader, but the first elected politician to be invited for two state visits.

“This is truly one of the highest honours of my life,” he said.

with AAP.