Alan Bennett takes swipe at National Trust in new play
Playwright's piece laments nation turned into 'captive market' where public life exhibits a 'diminution of magnanimity'Plays by Alan Bennett are an event: sold out months ahead and their subjects kept a closely guarded secret until the lights go up on the first performance.But ahead of the first preview of his latest work for the National Theatre the author has revealed that the play emerged as a result of disquiet a…