In 1806 the king, at the request of his son the prince of Wales, ordered an inquiry into rumours that the princess of Wales had given birth to a child. A number of men were suspected of having had a relationship with the princess (which was grounds for a charge of high treason), but it was Manby against whom the evidence was "particularly strong". Manby was called before the commissioners of the inquiry and swore on oath that he never did "at Montagu House, Southend, Ramsgate, East Cliff, or anywhere else, ever sleep in any house occupied by, or belonging to, HRH the Princess of Wales". The commissioners concluded that the main accusation against the princess was unfounded, but nevertheless they criticised her behaviour. The princess was defended by former attorney-general and future prime-minister Spencer Perceval, who dismissed the evidence of the princess's servants as 'hearsay representations'. The gifts and letters from the princess to Manby were evidence only of her gratitude for Manby having taken two of her charity boys on board the "Africaine", and his frequent visits were to keep the princess informed of their progress. If jugs of water and towels were left in the passage when Manby visited it was proof, Perceval argued, of the servants' slovenliness and not of high treason. Perceval was ready to publish his defence in the form of a book when there was a sudden change of government, the princess was accepted at court, and the book was suppressed. After Perceval's assassination in 1812 the book was published and extracts, including Manby's testimony, were published in the "Times".