Princess Anne is once again to step up to mark an important day on behalf of King Charles - while proving distance is not an issue when it comes to attending royal engagements and doing her duty. On Tuesday, the Princess Royal, acting as a Master of the Corporation of Trinity House, attended the organisation's event in central London.

But later on the same day, Princess Anne is scheduled to head from central London 400 miles north to Scotland, to host a garden party at the Palace of Holyroodhouse in Edinburgh, alongside Vice Admiral Sir Tim Laurence and King Charles and Queen Camilla. The first event of the day for the Princess Royal marked the annual IALA World Aids to Navigation Day, hosted by Trinity House and is a key part of the three-day celebration of maritime safety and innovation.

It holds particular significance as the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) has had an upgrade in its status.

It has now been changed from a Non-Governmental to an Intergovernmental Organisation. The new change is expected to provide exciting opportunities for stronger international cooperation at government level, relevant stakeholders and other international organisations.

The organisation intends to "bring together senior representatives of Government, the wider maritime industry, R&D establishments and academia, and international organisations such as the IMO to participate in interactive discussions".

Officially marked on July 1, the day's theme for this year is 'The role of physical Aids to Navigation in a Digital Future'.

The Garden Party will see King Charles welcome around 8,000 people from all walks of Scottish life to spend a relaxed afternoon with him in the beautiful grounds of the Palace in Edinburgh alongside Princess Anne and her husband.

The Royal Family will mingle and chat with guests, and the party is usually accompanied by music from regimental bands and The Royal Scottish Pipers Society.

King Charles and Queen Camila arrived by helicopter on Tuesday morning, where they were greeted by musicians from the Royal Regiment of Scotland - their week of engagements in Scotland is known as Royal Week.