CarolC --- I confess --- I WAS joking when I used the expression 'the revolting colonists' (though it is strictly accurate).
Ron --- You are entirely entitled to mistrust Mr Gardner, As I suggested, you could e-mail him via his website and ask his sources. If you wait for me to trace Gardner's book you may, I'm afraid, wait until random chance or the library angel puts it under my hand again. (I lshare a v.small house with thousands of books, records, tapes & videotapes).
Until that serendipitous moment arrives, I can only tell you (from memory) that a party of colonists who were quite willing to give King George the finger were not, apparently, convinced of the glories of republicanism. Either before or after offering the 'Crown of America' to G.Washington, the asked Charlie Stuart. He was immensely flattered, but said that, since he had no issue, on his death the British were likely to try and take America back. I think Gardner names the originator of the offer and I believe he says that Stuart was asked twice. Best I can do for the present.