The crazed ‘fan’ who attacked the singer waited patiently in the queue at Waterstones Piccadilly before launching himself at 24 year old Leona - but only after she had signed his book.
Security staff quickly restrained the thug while police arrived before the star was taken to a Harley Street Medical Clinic.
A spokeswoman said “Leona’s understandably badly shaken and apologises to the fans she was unable to meet and complete signings for.”