A man who sent a hoax "anthrax" letter to the prime minister has been jailed.
Vincent Potter, 60, of Mayfield, East Sussex, claimed the potentially lethal powder was in a letter to Theresa May.
Potter, who has schizophrenia, received an 18-month sentence at the Old Bailey, having admitted making a noxious substance hoax at a previous hearing.
The letter, written on a typewriter and posted at Gatwick in August 2017, was intercepted by postal workers. It was found not to contain anthrax.
Instead of using Mrs May's name in the letter he opted for an expletive, and signed it off as the "Brothers of the Right Hand".
Judge Rebecca Poulet QC said: "In my judgment, the person sending this frightening letter to the Prime Minister, intending them to fear for their safety, must be punished by immediate custody."
He was convicted 13 years ago for making an explosive, which the court heard was in relation to a dispute with a neighbour.
Judge Poulet said: "It is because of that background that I find myself unable to say that you do not present a risk or danger to the public."
Paula Bignall, defending, said in mitigation that Potter, who has 14 previous convictions for 25 offences including criminal damage and burglary, has "no real recollection of the events".
She said Potter, who had not been taking his medication at the time, was "filled with remorse, regret and to some extent a lack of understanding and comprehension as to how he committed the offence".