A Yorkshire private investigator voiced "racist, anti-Muslim and anti-immigration views" to his work colleagues and on social media, a jury at the Old Bailey heard.
Pawel Golaszewski, 34, from Armley in Leeds is on trial accused of possessing instruction manuals on making weaponry and killing techniques.
He denies six counts of possessing a document containing information useful for terrorist purposes under the Terrorism Act.
It is alleged that Golaszewski had copies of 21 Silent Techniques Of Killing by Master Hei Long, The Anarchist Cookbook and The Big Book Of Mischief.
He is also accused of having the Improvised Munitions Handbook, Murder Inc The Book by Jack The Rippa, and Mini-manual Of The Urban Guerrilla by Carlos Marighella.
Prosecuter Dan Pawson-Pounds said one of the documents gave "detailed instructions on how to kill people, as simple as that", while another contained instructions on how to "fight against a government".
Armed police stopped Golaszewski's car on Abbey Road, Leeds, on February 23 and arrested him on suspicion of terrorist offences.
They seized a laptop and tablet computer - devices on which the documents were found - as well as three sets of double looped tie-wraps, a folding pocket knife and a pair of chain link handcuffs.
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Searching his home in Armley, officers seized a survival knife in a sheath on a wall in the living room, two smoke grenades and a torch with a concealed knife in a desk drawer.
Mr Pawson-Pounds said Golaszewski, who appeared in the dock assisted by a Polish interpreter on Tuesday, told police at Eccleshill Police Station in Bradford that he was "not a terrorist" and the manuals were for professional research.
"I'm not a terrorist. In regards Britain First I'm not agreeing with their policies, their views and I think what they are doing is wrong," the defendant told police.
"In regards the manuals on my devices, I was doing research, general research as I wanted to join army forces.
"And also I was doing some general research as part of my business and work.
"In regards to smoke grenades, I bought them legally from UK shop and they were for paintball purposes and I'm taking part in paintball events."
Golaszewski, who was arrested while wearing a Nationwide Security Services uniform, claimed he obtained the documents as research for work as a security guard.
Mr Pawson-Pounds said: "The Crown's position is that there can be no legitimate reason for someone working in this industry, as a security guard or front door bouncer, to need to possess such material.
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"The world would be a very dangerous place if that was a legitimate reason."
Golaszewski also claimed the manuals were to assist his own private investigations company, PG Investigations, in tracing missing persons and debtors, serving legal documents, matrimonial cases and surveillance.
The jury was told that investigators found that, after speaking to the defendant's work colleagues and analysis of his Facebook account, he had voiced "anti-Muslim and anti-immigration" views.
Mr Pawson-Pounds said: "The defendant presents as a deeply bigoted individual, espousing far right causes and voicing racist, anti-Muslim and anti-immigration views."
Two copies of the Improvised Munitions Handbook were allegedly found on the defendant's laptop - one in a subfolder called "banned books collection" - and another copy was found on his tablet, where it had been downloaded in Kindle format.
An expert in explosions concluded that guidance in the 256-page document was "largely accurate and could be used to make viable explosive substances", the jury heard.
The trial continues.