Other variants on the Poyais scheme were similarly unsuccessful. In 1828 MacGregor began to sell certificates entitling the holders to "land in Poyais Proper" at five shillings per acre. Two years later King Robert Charles Frederic, who had succeeded his brother George Frederic Augustus in 1824, issued thousands of certificates covering the same territory and offered them to lumber companies in London, directly competing with MacGregor. When the original investors demanded their long-overdue interest, MacGregor could only pay with more certificates. Other charlatans soon caught on and set up their own rival "Poyaisian offices" in London, offering land debentures in competition with both MacGregor and the Mosquito king. By 1834 MacGregor was back in Scotland and living in Edinburgh. He paid some unredeemed securities by issuing yet another series of Poyaisian land certificates. Two years later he published a constitution for a smaller Poyaisian republic, centred on the region surrounding the Black River, and headed by himself as President. It was clear, however, that "Poyais had had its day," as Sinclair puts it. An attempt by MacGregor to sell some land certificates in 1837 marks the last record of any Poyais scheme.