David Baldwin has written a pretty good biography on Elizabeth Woodville, Queen Consort of Edward IV and mother of the princes in the Tower. In appendix 6 of this biography he devotes a chapter to the disappearance of the princes. However, it must have rankled in his mind that he did not find a convincing explanation what happened to Edward V and his brother Prince Richard;, Duke of York. So in a way "The Lost Prince" is a follow-up of his biography of Queen Elizabeth Woodville.
His hypothesis is that Edward V died properly of natural cause while his younger brother and rightful heir of the York dynasty survived as the bricklayer Richard in Colchester and Eastwell and this with the full knowledge of the Tudor monarchs. All is based on the story that this Richard was discovered by Sir Thomas Moyle of being in command of Latin - how come as a mere bricklayer? - and this Richard told him the story that he was brought to king Richard III just before the battle of Bothwell and told by the king that he was his son.
David Baldwin sets out to prove this story. Of course, he has first to try to explain how his Richard was not the bastard son of Richard III but the legitimate son of Edward IV. Then he has to construct a whole story how Prince Richard was brought to safety; protected through the various ups and downs of English history which have costs other claimants to the throne easily their lives.
Does he succeed? I believe not at all. This book is full of maybes, assumption, half truth. As with all this books on historical mysteries there are always open questions and this creates the opportunity for speculation. The system is always the same: one assumes a fact (here the survival of the Prince Richard as Richard of Eastwell). Then one tries to prove this "fact" by finding certain less clear other facts ( f.e. trip by Queen Katherine of Aragon through Colchester even tough that was not the most straight forward route to take to her destination) and gives that the only explanation surviving the purpose that this must have taken place because here the lost prince was living. Here a perfect, but false circle is created. And indeed David Baldwin has NO concrete fact that proves his theory. This is nothing but guesswork, nicely presented, but not at all convincing.
Oscar Handlin said once that history is the distillation of evidence surviving the past. Here no hard evidence is presented that Prince Richard had survived and David Baldwin fails to prove his theory. A theory is no prove.