In the legal notice released to the media here, Benson said by calling Singh night watchman, Modi has "insulted, degraded and defamed" in public the image and good reputation of Prime Minister's post.
Without naming Manmohan Singh, Modi on March 3 had said the Congress appointed a "night watchman" to keep the seat warm for the first family of the Congress. "They did not realise that the night will be so long and dark. As a buffer, they appointed an economist to the post," he said.