It is understood that MI6 is comparing The Big Breach with the manuscript written by Tomlinson five years ago. The FSB almost certainly inserted passages into the book. Last week the Court of Appeal in London ruled that secrets disclosed in Tomlinson's book could be published in Britain. The credibility of Tomlinson's book, however, is in tatters already even before it goes on sale. The allegation that MI6 was implicated in the death of Diana, Princess of Wales, had been dismissed as "ludicrous" by the secret intelligence service.