King Haakon of Norway (by then an elderly widower) and his son Crown Prince Olav can be added. Olav in particular had a fine record:Other monarchs had more difficult choices to make, when their country was overrun.
Dutch Queen Wilhelmina fled to England and continued the war from there. She was critisized for leaving the population behind.
Belgian King Leopold capitulated, refused to follow his government to London and 'stayed with his troops'. He was critisized for it, as he had to deal with German occupation politics.
Crown Prince Olav and his father, King Haakon, were very close, and the Crown Prince was an important source of support for and trusted advisor to the King, particularly during WWII.
In the 1930s the King and Crown Prince were concerned about the state of the Norwegian defence capacity. They had sought support for a strengthening of military forces, but to no avail. When German troops invaded Norway on 9 April 1940, the King and Crown Prince accompanied the Norwegian troops as they withdrew northwards, and later to London during the time in exile.
Crown Prince Olav travelled together with the King and the Government to London. It was difficult for the Crown Prince to leave his country, and he offered to remain in Norway. Most of all, he wanted to fight on the front lines, but the Government strongly advised against it. While in exile the Crown Prince was able to make major contributions to Norway’s defence both militarily and diplomatically.
In 1939 the Crown Prince and Crown Princess had conducted a comprehensive tour of the USA. During that journey they had made the acquaintance of President Franklin D. Roosevelt, thus laying the foundation for a long-lasting friendship. This friendship proved to be of great importance to Norway during WWII, as it facilitated direct contact with the US president. In 1942 the Crown Prince conducted another lengthy tour of the USA, lecturing on the Norwegian fight for liberation.
On 30 June 1944 the Government in exile in London appointed Crown Prince Olav Chief of the Defence. He overtook leadership of the Norwegian armed forces and cooperated with the Allied Powers.
As the war drew to a close, the Crown Prince worked tirelessly to secure Allied guarantees to provide rapid and adequate support to Norway should the country become a final battleground once the war on the Continent had been won. Fortunately, the need for such support never materialised.
On 13 May 1945 Crown Prince Olav and five government ministers returned to a liberated Norway. Cheering crowds lined the route of the procession as it wound its way from the harbour. The Crown Prince acted as Regent until King Haakon’s return on 7 June.