The Queen has been laid to rest in the royal vault of St George's Chapel, drawing an end to the day that Britain said farewell to its longest-reigning monarch.

The private burial ceremony took place behind closed doors after a day of ceremony that began with the state funeral at Westminster Abbey this morning.

The state funeral was attended by 2,000 guests, among them the King and immediate members of the royal family, world leaders, dignitaries and European royalty.

Hundreds of thousands lined the route of the procession taking the Queen's coffin from the abbey to St George's Chapel inside Windsor Castle. 

After the coffin's arrival at the chapel, a committal service was conducted by the Dean of Windsor, David Conner. The Archbishop of Canterbury gave the blessing.

The Queen was laid to rest in the King George VI Memorial Chapel, which sits within St George's Chapel in Windsor Castle.

The Crown Jewels were removed from the top of the coffin before it was lowered into the chapel's royal vault where the Queen was reunited with her late husband, Prince Philip.

The private burial on Monday evening was marked by an intimate service of prayers and hymns attended by members of the royal family.

Unlike the earlier services, this one was not televised and was closed off to the media, with Buckingham Palace calling it a "deeply personal family occasion".

A brief statement from the royal family's website said, "The Queen was buried together with the Duke of Edinburgh, at The King George VI Memorial Chapel."

At the state funeral earlier in the day, the Archbishop of Canterbury, the Most Rev Justin Welby, said the Queen had touched "a multitude of lives".

"The pattern for many leaders is to be exalted in life and forgotten after death," the Archbishop said.

"Her late Majesty's example was not set through her position or her ambition but through whom she followed."

He continued, "We will all face the merciful judgement of God. We can all share the Queen's hope which in life and death inspired her servant leadership - service in life, hope in death.

"All who follow the Queen's example and inspiration of trust and faith in God can with her say, we will meet again."

Some two million people are believed to have poured into London on the day of the funeral, with thousands watching the historic occasion on large screens in Hyde Park. 

Churches and cathedrals up and down the country also livestreamed the funeral for members of the public.