Here are some sample army service numbers and corresponding joining dates for the Essex Yeomanry.
10 joined on 1st April 1908
444 joined on 15th January 1909
605 joined on 17th May 1910
647 joined on 21st January 1911
859 joined on 2nd January 1913
1070 joined on 5th August 1914
1374 joined on 8th October 1914
1590 joined on 9th November 1914
1666 joined on 7th December 1914
1777 joined on 9th January 1915
1919 joined on 2nd March 1915
2074 joined on 7th April 1915
2272 joined on 29th June 1915
2406 joined on 21st October 1915
There are a couple of points to note about this brief sequence above. The first is that the huge influx into the regiment by 1909 (444 recruits in the months April 1908 to January 1909) is explained by men from the old Essex Imperial Yeomanry, joining the new Essex Yeomanry. Just as men from the pre-1908 Volunteers (infantry) were encouraged to re-enlist with newly formed Territorial Force battalions, so most of those 444 Essex Yeomanry men would have previously served with the Essex Imperial Yeomanry. There is a brief overview of the Essex Yeomanry on Wikipedia and the Essex Yeomanry Association is here.
By 1910, enlistments into the Essex Yeomanry had steadied drastically, with just 30 new recruits issued numbers between May and December that year. Recruiting picked up again of course during the First World War, but even by March 1917, the numbers - again, as to be expected - were far lower than in the Essex Regiment Territorial Force battalions. The last four-digit number I have on my database for The Essex Yeomanry is 2825 which was issued on 17th March 1917.
Find photos of Essex Yeomanry soldiers on my British Army Ancestors website.
THE 10th (P.W.O.) ROYAL HUSSARS AND THE ESSEX YEOMANRY DURING THE EUROPEAN WAR, 1914-1918.
This from the Naval & Military Press:
"A Regular cavalry regiment and a Territorial Yeomanry regiment make strange bedfellows in a combined regimental history, but this is the work of an officer who commanded both during the war and felt the need to make a record of the incidents which united the Regiments in close friendship during the Great War. Whitmore was a Territorial officer, not a Regular, and his appointment to command a regular cavalry regiment must have been a unique one; there were only twenty-five cavalry of the line regiments on the Western Front and competition for command among career officers would have been keen. Furthermore he was recommended to the command of the 10th Hussars by the Cavalry Corps commander, Lieut-General Sir Charles Kavanagh, who was himself a former CO of the Regiment.
"The Hussars landed at Ostend in October 1914, the Essex at Havre on 1 December 1914 and both regiments served in 8th Cavalry Brigade, 3rd Cavalry Division, till April 1918 when the Essex were broken up, at which point Whitmore, who had been CO of the Essex since November 1915, was posted to command 10th Hussars where he remained till March 1919.
"This account is not in the form of a personal memoir but rather that of an impersonal, wartime regimental history in which the activities of both regiments are fused into the one narrative set out in chronological order. There is a wealth of information in the appendices which are arranged for each Regiment separately: Diary of movements; Roll of officers who served showing when they joined and when they left and whether they were casualties and, in the case of the Essex; where they went; Honours and Awards; list of casualties showing killed, wounded or missing. There are also two appendices showing Order of Battle, one giving names of Cavalry Corps, Division and Brigade commanders with dates, and the other giving the composition of the Cavalry Divisions and Brigades. There is an index. This is a gift for researchers, genealogists and medallists."
I also offer a comprehensive, fast and cost-effective military history research service. Follow the link for more information.
It is wrong to assume that numbering sequences in battalions always followed a sequential pattern. They didn't. As the war progressed and casualties grew, large numbers of men were often transferred from one battalion to another and allocated numbers within blocks which did not fit the sequential patterning seen to date. This becomes particularly evident in most battalions from 1916 onwards. For an example of this, see my post on the 23rd London Regiment.