The QUEEN has welcomed the UK's new £3.1 billion aircraft carrier into the Royal Navy fleet and declared it the "best of British".

Accompanied by the Princess Royal, the Queen arrived on board HMS Queen Elizabeth at Portsmouth Naval Base earlier today using a specially installed lift to bring her up to the hangar for the occasion.

Wearing a purple outfit, she was led onboard by the ship's commanding officer Captain Jerry Kyd.

Defence Secretary Gavin Williamson also attended to witness the 65,000 tonne vessel joining the fleet.

At 280 metres long and with an estimated half a century working life, the behemoth warship is the biggest and most powerful ever built by the UK.

A total of 3,700 guests including families and VIPs gathered in the ship's giant hall for the ceremony.

In a speech, the Queen said: "We are gathered here in Portsmouth today just a short distance from HMS Victory, a flagship of our seafaring past and a reminder of the debt we owe to the Royal Navy which for more than 500 years has protected the people of this country and our interests around the world.

"Like HMS Victory, HMS Queen Elizabeth embodies the best of British technology and innovation, a true flagship for the 21st century.

"The most powerful and capable ship ever to raise the White Ensign, she will in the years and decades ahead represent the country's resolve on the global stage."

The ceremony was organised to commission the carrier into the fleet but the Aircraft Carrier Alliance confirmed that the Royal Navy had formally accepted the ship on Thursday, meaning it had been fully handed over to the Ministry of Defence.

Mr Williamson said the commissioning ceremony "marks the start of a hugely significant chapter for the Royal Navy".

He added: "Our new aircraft carrier is the epitome of British design and dexterity, at the core of our efforts to build an Armed Forces fit for the future."

On the Queen's arrival, the national anthem was played before she, along with Anne, inspected a guard on parade.

The Queen then received the royal salute as the ensign was raised for the first time on the flight deck, broadcast into the hangar on large screens.

An audible sigh of relief could be heard from the ship's company as the ensign, initially slightly entangled, opened out fully and flew freely in the wind.

On show were cakes created for the event including a model of the carrier and others depicting the Queen and sailors on parade, including one who has fallen on his face after fainting.

The ceremony finished with the cake representing the ship being cut by the commanding officer's wife Karen Kyd and the youngest member of the ship's company Steward Callum Hui, 17, from Lynton, Devon.