The Spy School at Hounslow was operated by MI5. Agents received a short course of theoretical and practical instruction on their undercover work in Ireland. They would then be sent to Ireland in various roles. By the nature of it, nobody has written an history of the Spy School. They were then sent to Ireland to operate in plain clothes and living in the community Winter wrote in "Report on Intelligence Branch" that about 60 men were sent to Irelnd via this route over a 8 or 9 month period, and that only 1 met a violent death
Set up in Jun 1920, it was originally run by Charles A Tegart and Godfrey C Denham until Nov 1920. They were both well respected intelligence professionals in the Indian Colonial Police. London requested their release for temporary service in Ireland to bolster Winter in his role as chief of the Combined Intelligence Service in Ireland. Tegart was Irish by birth . For a number of reasons they resigned in Nov 1920, and the running was taken over byand Cameron and Jeffries until Mar 1921, when it appears to have been closed. Jeune mentions meeting Cameron and Jeffries early in 1921. Peel's joining orders show that Harper Shove is here from Jun 1920 - he probably left in Nov 1920, from his next LG entry
And Halestrap's leaving records that all correspondence should be through War Office Room 419.AR Boscawen Savage. had similar instructions. So these men were being protected from prying eyes
This WW1 Forum thread goes into some detail of Room 419. Room 419 was one of a number occupied by MI7. In May 1918 the occupant was a Capt P Chalmers Mitchell. (Allocation of Rooms with List of Officials Employed at the War Office, May 1918) Fortunately, there is a report by him about his work there in 1917:
The 10th Royal Fusiliers, where Intlligence Agent recruits for Ireland were based, was used a cover for various things.O'Neill in his History of Royal Fusiliers, says that the 10th was used as the administration for the soldiers, many ex Scotland Yard and others with good language and translation skills. Since there was not an Intelligence Corps per se these men were held on the books of the 10th Royal Fusiliers. Why this particular battalion, in which the Special Branch men never actually served, was chosen is not clear.
This is probably also the House Guards/Whitehall court Spy School that Jeffries CV refers to Major later Brig William Francis Jeffries 1891 - 1969. Intelligence Dublin and Horse Guards 1920 to 1921.
Biggs has an address "Horse Guards Annexe, Carlton House Terrace, London SW1" in 1919 which I am fairly sure is the Spy School. .Headquarters, London District, Horse Guards Annexe, 12, Carlton House Terrace, London, S.W.I. 17th December, 1918. http://en.wikipedia.org/wiki/Carlton_House_Terrace
ROYAL FUSILIERS (10th SERVICE BATTALION). Hansard 6 Jul 1915
Mr. NIELD asked the Under-Secretary of State for War (1) whether the standard of efficiency of the non-commissioned officers and men of the 10th Service Battalion of the Royal Fusiliers is so high that already and under very restrictive administration nearly 200 commissions have been granted to men; whether he is aware that there are no less than 600 of the men of this battalion who are in every respect competent to receive commissions and who are of much more value than the many persons who are daily receiving commissions; and whether, having regard to these circumstances and also to the suitability of the men from a social point of view, he will cause the restrictions which at present preclude these men applying for commissions to be removed; and (2) whether, owing to the standard of efficiency attained by the non-commissioned rank and file in the 10th Service Battalion of the Royal Fusiliers and having regard to the circumstances that socially and in all other respects they are of the class from which the best officers are obtained, he will consider if the interests of the country will be better served by offering commissions to such of the rank and file of this battalion as are desirous of accepting them, and so distributing them over various regiments rather than sacrificing these men as a unit to the exigencies of service in the field?
Mr. TENNANT Commissions have been granted to a considerable number of noncommissioned officers and men of the 10th Battalion Royal Fusiliers, and recommendations are still being received from the commanding officer of that battalion, who has instructions to submit the names of all soldiers serving in his unit who are candidates for appointment to commissions and whom he can recommend as in all respects suitable for such appointment, provided the efficiency of the unit as a whole does not suffer. I do not know what the number may be of those who are eligible for recommendation on these conditions, but I am sure the hon. Gentleman will recognise that it must be left to the commanding officer to decide whether any particular soldier shall or shall not be recommended at once for a commission.
"The Royal fusiliers in the great war" O'Neill
Its description was " 10th Battalion Royal Fusiliers or Intelligence B," abbreviated I (b). It seems, like Topsy, to have just " growed." The first nucleus was provided by a small body of men from Scotland Yard especially selected for their knowledge of French and German. It performed mysterious and wonderful things, such as forming the buffer state between a colonel and a babel of tongues. This representative of I (b), a professor of languages, had to explain any lapses from discipline to the colonel, and any punishments inflicted on behalf of discipline to the recruits who were possessed of the gift of tongues. The latter appears to have been the more wearing task, though only by a shade. In France their work consisted in the detection of German agents. Working generally in civilian clothes, the small nucleus expanded into a numerous body of officers and men, recruited for their knowledge of languages, from various units. In civil life these men represented the oddest mixture of classes. There were some of those mere idlers who pick up a variety of languages from their penchant for travel. One was a travelling showman of Russian bears, who piloted performing bears from the extreme north to the southernmost point of Europe. Another was an Anglo-Armenian sergeant, born in France and educated in Czecho-Slovakia and Italy. Another was a strange cross of Aberdeen and Naples. This aggregation of strange types was at length placed for administrative purposes in one unit, the ioth (b) Royal Fusiliers. Beginning in France, where their counter- espionage work did much to make our intelligence work almost invariably superior to that of the enemy, I (b) gradually spread to Italy, Salonika, the East, and, finally, to Russia.