In reply to a query on Tring I said that in my book The London Gunners come to Town life in Hemel Hempstead during the First World War is described in detail, and the situation in most other Hertfordshire towns was very similar.

Many local men were members of the local territorial force before the war or joined it soon after the war broke out. The "F" company of the Hertfordshire Regiment came from Hemel Hempstead, Berkhamsted, Tring and Ashridge, and definitely included a unit from Tring. There were two territorial Hertfordshire Royal Field Artillery batteries. One was based at St Albans and the other at Watford, and I am pretty sure that any Tring members would have joined the Watford unit. There was also the Hertfordshire Yeomanry (cavalry)

In addition various territorial units were billeted in the Tring area once war had broken out - although these came from a different Division to those at Hemel Hempstead - and each unit would have been keen to recruit young men. Definitely quite a lot of young men in Hemel Hempstead joined the Royal Field Artillery units billeted in the town, and I have no reason to think matters were any different in Tring. (The local pubs would have been full of soldiers, encouraging others to join them.)

In addition there may have been a separate recruiting office and there would have been special recruiting events. There is also the possibility of recruiting in Aylesbury - which is not far from Tring.

When I was researching the First World War I found two booklets "World War I Army Ancestry" and "More Sources of World War I Army Ancestry" by Norman Holding very helpful. I am sure that these (or some more recent booklets) will be available from the Society of Genealogy Online Bookshop).