Conrad had become a personal friend of Stewart Menzies, who later (in 1939) was named head of the British Secret Service.
He persuaded Conrad to rejoin the Secret Service (now as Agent Z3), and provided him with the cover of businessman.
The newly formed Secret Intelligence Service (SIS) network "Z" was taking shape under a variety of business covers, and Conrad established Tyrolese Tours offering package tours to Austria and Southern Germany.
He based himself in Kitzbühel and proceeded to establish a spy network stretching from Austria deep into Southern Germany.
While in Kitzbühel, Conrad met Peter Fleming and Ian Fleming, and they often crossed paths at homes of mutual friends, at bars, on the ski slopes or at the warm-water lake, the Schwarzsee.
Conrad's style, athletic endeavours, personal adventures and experience in espionage may have provided Ian Fleming with some of his inspirations for James Bond.
He was also in attendance to Edward VIII and Wallis Simpson, who used Kitzbühel as their first home after the abdication crisis of 1936.

Conrad provided intelligence on Nazi occultism and the build up of German forces in preparation for World War II.
On Friday, 11 March 1938, Conrad received a message from an Austrian living near the Austrian/German border, reporting that German forces were advancing from Bad Tölz and Rosenheim towards the Austrian border.
The timeliness of this information is critical to political and military manoeuvres.
Knowing this, Conrad used the most expedient method available to transmit the message, phoning the report directly to London, even though it exposed his cover.
He was told that this was the first news received from Allied capitals reporting the advance.
Conrad continued to receive confirmations of the advance throughout the day.
Through his local contacts he was able to warn residents, giving many in danger time to quickly pack and flee—saving lives.
The ease of travel quickly changed, and by the next morning Gestapo officials were ripping soles from passengers' shoes in search of money and incriminating documents.
At 9 a.m., Saturday morning, 12 March, a large force of German troops entered Kitzbühel, with another at Mittenwald to occupy Innsbruck and the country west as far as the Arlberg Pass.

Himmler's Gestapo, in 1940, prepared for Nazi Germany's invasion of Britain in World War II by compiling a list of more than 2,300 names of the most-wanted Britons in The Black Book (Sonderfahndungsliste G.B.).
It includes the name of French, Marquis de Castelchomond (sic), O'Brien with the notation "brit.
Agent, Kapitän."
The 112th entry continues with "vermutl.
England, RSHA IV E4 Stapoleit München."
The Reich Main Security Office, RSHA, combined the SS Intelligence Service (the SD), Secret State Police (Gestapo), Criminal Police (Kripo) and Foreign Intelligence Service into an enormous organization, armed with the data and resources to commit mass murders.
The RSHA coding system reveals the last of the entry, with "IV E4" meaning "Counter-Intelligence in Scandinavia."
Conrad's cover as a spy was compromised after the Austrian Anschluss of 1938, and he retired from the intelligence services soon after.

During the war O'Brien-ffrench also served as Imperial censor in Trinidad.
Conrad had become a personal friend of Stewart Menzies, who later (in 1939) was named head of the British Secret Service. He persuaded Conrad to rejoin the Secret Service (now as Agent Z3), and provided him with the cover of businessman. The newly formed Secret Intelligence Service (SIS) network "Z" was taking shape under a variety of business covers, and Conrad established Tyrolese Tours offering package tours to Austria and Southern Germany. He based himself in Kitzbühel and proceeded to establish a spy network stretching from Austria deep into Southern Germany. While in Kitzbühel, Conrad met Peter Fleming and Ian Fleming, and they often crossed paths at homes of mutual friends, at bars, on the ski slopes or at the warm-water lake, the Schwarzsee. Conrad's style, athletic endeavours, personal adventures and experience in espionage may have provided Ian Fleming with some of his inspirations for James Bond. He was also in attendance to Edward VIII and Wallis Simpson, who used Kitzbühel as their first home after the abdication crisis of 1936.
Conrad provided intelligence on Nazi occultism and the build up of German forces in preparation for World War II. On Friday, 11 March 1938, Conrad received a message from an Austrian living near the Austrian/German border, reporting that German forces were advancing from Bad Tölz and Rosenheim towards the Austrian border. The timeliness of this information is critical to political and military manoeuvres. Knowing this, Conrad used the most expedient method available to transmit the message, phoning the report directly to London, even though it exposed his cover. He was told that this was the first news received from Allied capitals reporting the advance. Conrad continued to receive confirmations of the advance throughout the day. Through his local contacts he was able to warn residents, giving many in danger time to quickly pack and flee—saving lives. The ease of travel quickly changed, and by the next morning Gestapo officials were ripping soles from passengers' shoes in search of money and incriminating documents. At 9 a.m., Saturday morning, 12 March, a large force of German troops entered Kitzbühel, with another at Mittenwald to occupy Innsbruck and the country west as far as the Arlberg Pass.
Himmler's Gestapo, in 1940, prepared for Nazi Germany's invasion of Britain in World War II by compiling a list of more than 2,300 names of the most-wanted Britons in The Black Book (Sonderfahndungsliste G.B.). It includes the name of French, Marquis de Castelchomond (sic), O'Brien with the notation "brit. Agent, Kapitän." The 112th entry continues with "vermutl. England, RSHA IV E4 Stapoleit München." The Reich Main Security Office, RSHA, combined the SS Intelligence Service (the SD), Secret State Police (Gestapo), Criminal Police (Kripo) and Foreign Intelligence Service into an enormous organization, armed with the data and resources to commit mass murders. The RSHA coding system reveals the last of the entry, with "IV E4" meaning "Counter-Intelligence in Scandinavia." Conrad's cover as a spy was compromised after the Austrian Anschluss of 1938, and he retired from the intelligence services soon after.
During the war O'Brien-ffrench also served as Imperial censor in Trinidad.
Conrad O'Brien-ffrench