The festival, which takes place at venues across the town, runs from September 28 to October 4.
Latest additions to the line-up include Max Mosley in conversation with Anne Robinson, Prue Leith, a look back at the coalition with Norman Baker, Ann Treneman and Polly Toynbee, Ralph Steadman, a special Downton event at Fawley Court.
Also on the bill is David Nobbs, Emma Kennedy and Robin Esser in conversation with Michael Parkinson.
They join previously confirmed speakers including Brian Blessed, John Sentamu, Sue Perkins, Ella Woodward and Lynda La Plante.
Events for children aged two and up include Charlie & Lola with creator Lauren Child, Famous Five, Beast Quest, Hugless Douglas, Alice in Wonderland, Kipper and many more.