The Queen makes surprise trip to London to open Elizabeth Line with Prince Edward

The Queen travelled to London on Tuesday to open the new Elizabeth Line with her youngest son Prince Edward. Despite her ongoing mobility issues, the 96-year-old monarch, who was not previously expected to make the trip, decided at the last minute to travel from her home in Windsor, stunning commuters, tourists and passers-by as she arrived at Paddington Station.

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The royals, who were marking the completion of London's Crossrail project, were greeted by Prime Minister Boris Johnson, Mayor of London Sadiq Khan and Transport for London commissioner Andy Byford.

During the engagement, the monarch bought the first ticket for the Elizabeth line using a commemorative Oyster card and unveiled a plaque to mark the opening.

Her son Edward then boarded a train bound for Tottenham Court Road station before returning to Paddington, while the Queen only stayed at the engagement for ten minutes.

See the best photos from their outing below…

WATCH: The Queen officially opens the Elizabeth line in surprise last-minute outing

It was unclear whether the Queen would be able to attend Tuesday's engagement, so royal watchers were no doubt thrilled to see Her Majesty in great spirits as she made the trip to the capital.

A Buckingham Palace spokeswoman said: "In a happy development, Her Majesty The Queen is attending today's event to mark the completion of the Elizabeth line.

"Her Majesty was aware of the engagement and the organisers were informed of the possibility she may attend."

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She and Prince Edward were given a warm welcome at Paddington station, where they spoke to train drivers, station staff and apprentices who were involved with the Crossrail project.

The monarch looked typically polished wearing a Stewart Parvin double-wool crepe coat in sunshine yellow, with an A-line silk dress in shades of yellow, royal blue and turquoise, and a matching hat by Rachel Trevor-Morgan.

She was wearing her Singapore brooch.

With the help of her walking stick, she walked slowly around the station concourse.

The Queen unveiled a plaque while her son Prince Edward stood alongside her.

She then used a commemorative Oyster card to purchase the Elizabeth line's first ticket.

The new trainline will open to the public on 24 May.

During the brief engagement, the Queen spent around ten minutes at Paddington before departing in a lift, escorted by her son Edward.

Edward then returned to the station concourse to board the return journey from Paddington to Tottenham Court Road.

Following the Queen's visit, Boris Johnson told the invited guests: "We're all incredibly touched and moved and grateful to her Majesty for coming to open the Elizabeth line today. "It was fantastic to see her."

Crossrail, the project to build the new east-west railway, was delayed and over budget due to numerous issues including construction difficulties and complications installing signalling systems.

It was due to be completed in December 2018 and was set a budget of £14.8 billion in 2010. However, the total cost has been estimated at £18.9 billion, including £5.1 billion from the government.

The Elizabeth line will boost capacity and cut journey times for travel across the capital. It will stretch from Reading, in Berkshire, and Heathrow Airport, in west London, to Shenfield, in Essex, and Abbey Wood, in south-east London.