The firebombing of an immigration processing centre in Dover has been declared a terrorist incident after police found evidence the attack was motivated by an extreme right-wing ideology.Andrew Leak, 66, from High Wycombe, is believed to have killed himself at a nearby petrol station after throwing two or three “crude” incendiary devices at the site in Kent last Sunday.Counter Terrorism Policing South East said on Saturday that evidence had been recovered that indicated the attack “was motivated by a terrorist ideology”.Police said there was no evidence of any wider threat to the public.