Scottish football fans booed God Save the King just hours before Charles made yet another visit north of the border.
King Charles, who is still on his summer break to Balmoral in Aberdeenshire, will visit Tomintoul in the Cairngorms National Park.
The 74-year-old will also join primary school children and community stalwarts.
However, fans crammed into Glasgow's Hampden Park appeared to voice their opposition to the monarchy.
Scotland and England players observe a minutes silence during the 150th Anniversary Heritage international friendly match at Hampden Park, Glasgow
PA
The Tartan Army drowned out almost 3,000 England fans who belted out God Save the King.
The Three Lions ultimately prevailed in the 150th anniversary fixture of the first football international with a 3-1 away victory for the Auld Enemy.
Phil Foden opened the scoring with little over half-an-hour gone after Kyle Walker's shot deflected off his Manchester City teammate.
Scottish supporters were silenced just seconds later when Jude Bellingham pounced on sloppy defending by Liverpool's Andy Robertson.
Jude Bellingham celebrates scoring his sides second goal during the international friendly match at Hampden Park, Glasgow
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Harry Maguire accidentally placed the ball in the back of his own net in the second half the give Steve Clarke's side hope.
However, England's all-time top goalscorer Harry Kane tucked the ball into the bottom corner to restore the Three Lions' two goal lead.
England's unbeaten run against Scotland has now been extended to six matches, with the Tartan Army last tasting victory over the Auld Enemy at Wembley in 1999.
Scotland's last home victory over England came in 1985 when Richard Gough proved the difference at Hampden Park.
England fans were able to avenge the Tartan Army's pre-game antics by singing the national anthem as Scottish supporters started to leave the 51,866-seater stadium.
England fans celebrating during their victory over Scotland
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Despite Scots booing God Save the King, the 278-year-old song has represented the entirety of the United Kingdom since the beginning of the nineteenth-century.
The original lyrics also included a line about crushing "rebellious Scots" as it was written around the time of the Jacobite uprising of 1745.
England and Northern Ireland are the only two Home Nations who sing God Save the King ahead of kick-off.
The Scottish Football Association adopted Flower of Scotland, which refers to Robert I's victory over Edward II at Bannockburn in 1314, as its pre-game anthem in 1997.
Wales meanwhile brought singing the national anthem to the sporting world in 1905 as fans and players belted out Hen Wlad Fy Nhadau ahead of New Zealand's defeat in 1905.