The November 10 1927 edition of the Toronto Daily Star contained this photo of a Balkan royal out on a visit:
The caption for this photograph mentions that George, Crown Prince of Serbia (1887-1972) renounced his rights to the Serbian throne in 1909, but it did not say why. It turns out that the reason was ugly, to put it mildly: in a fit of temper, Prince George kicked his valet to death. He apparently tried to take back his succession rights after that, but was refused – which is understandable, given the circumstances.
Prince George’s Wikipedia page states that he was arrested in 1925 after his brother was crowned King of Serbia, and that he was in an asylum from then until the start of the Second World War. This contradicts the photo above, which claims that he visited Cherbourg in 1927. I have no idea what is going on here.
I can tell you that Prince George did not marry Mrs. Dorothy C. Cochrane (about whom I could find nothing). He did eventually marry Radmila Radonjić in 1947.