The public appearance is Harry’s first since he and wife Meghan Markle decided to step back from royal duties and become more financially independent.

The event will also mark the Prince’s final engagement as a senior royal, before the spring 2020 transition takes effect on 31 March.

He has not travelled with his partner or his son, Archie.

Prince Harry meets well wishers during a walkabout on the esplanade at Edinburgh Castle in 2018 (Photo: Andrew Milligan - WPA Pool/Getty Images)

Here's everything you need to know about the visit:

What is Harry doing in Edinburgh?

The Duke of Sussex is due to host a summit on sustainable and ethical tourism in the capital.

He joined forces with Booking.com, SkyScanner, CTrip, TripAdvisor and Visa to try to encourage travellers to make “environmentally friendly choices” when booking trips.

The key aims of his Travalyst initiative, launched in September, include “supporting local people, protecting wildlife, tackling climate change and environmental damage, and alleviating overtourism.”

Around 100 representatives of the tourism and travel sector are expected to attend the eco-tourism summit at the Edinburgh International Conference Centre tomorrow, which is being jointly staged by Travalyst, the EICC and tourism agency VisitScotland.

As well as issues about how the growth of tourism has affected Edinburgh, the summit is expected to look at other parts of the country which have struggled with a swift increase in visitors.

Why Edinburgh?

His choosing of Edinburgh as the location for the summit comes less than a year after it was named one of the world’s worst-affected overtourism hotspots, along with the likes of Amsterdam, Rome, Venice and Barcelona.

It was also cited alongside the Taj Mahal, in India, the Peruvian citadel of Machu Picchu, Dubrovnik, in Croatia, and Iceland as famous destinations "that can no longer cope with their own popularity."

Malcolm Roughead, chief executive of VisitScotland, said: “We are delighted to be facilitating Travalyst’s very first working meeting here in Scotland.”

“The Travalyst team approached VisitScotland not only due to Scotland’s prominence and success as a renowned destination for all levels of traveller, but specifically for our work in addressing some of the opportunities and challenges that can arise.

Where is he?

The summit is taking place at the Edinburgh International Conference Centre.

Prince Harry surprised Scots yesterday evening (25 February) as he walked through the Capital's main railway station carrying his bags.

He was pictured sporting a black jacket and cap after getting off a train in the city centre.

The Scottish dry-wit was out in force as Edinburgh locals offered the Duke of Sussex some friendly pointers.

Arron Neve wrote: “Good luck finding your platform, lad.”

Gordon Craig has his eyes on a meeting with Harry, saying: “Top bloke, would love to go for a pint with him.”

Alan Inverarity was expecting him, writing: “Heading to my gaff for dinner. Spag bol and artic roll.”

What will happen at the event?

A spokeswoman for Travalyst said: “Key stakeholders in travel and tourism from across Scotland have been invited to come together for a series of workshops and discussions to explore the sustainability challenges and opportunities at hand, gather critical feedback on the principles and frameworks that have been developed thus far and begin designing pilot projects for further collaboration in Scotland.

"Sessions will also include discussion on the challenges and opportunities around ensuring Scotland receives socio-economic benefits from travel, with an exploration of some of the activities of local social entrepreneurs.”

Roughead said: “We and the host venue of the EICC look forward to welcoming the Duke of Sussex and the Travalyst partners to Scotland, and contributing to this important debate.”

Prince Harry in Edinburgh: why the Duke of Sussex is visiting Scotland’s capital today