The Group Scheme
By spring 1915 the flow of volunteer recruits was dwindling. The government, torn when it came to the question of compulsory military service, tried a half-way house scheme.
Voluntary recruitment was drying up
In spring 1915 enlistments had averaged 100,000 men per month, but this could not be sustained. The upper age limit was raised from 38 to 40 in May 1915 in an effort to keep the numbers up, but it had became clear that voluntary recruitment was not going to provide the numbers of men required. The government passed the National Registration Act on 15 July 1915 as a step towards stimulating recruitment and to discover how many men between the ages of 15 and 65 were engaged in each trade. All those in this age range who were not already in the military were obliged to register, giving details of their employment details. The results of this census became available by mid-September 1915 : it showed there were almost 5 million males of military age who were not in the forces, of which 1.6m were in the "starred" (protected, high or scarce skill) jobs.

Born in 1865, Edward Stanley became the 17th Lord Derby in 1908. He played a major part in raising volunteers, especially for the King's (Liverpool) Regiment, before being appointed Director-General of Recruiting in October 1915.
On 11 October 1915 Lord Derby was appointed Director-General of Recruiting. He brought forward a programme five days later, often called the Derby Scheme although its official title was the Group Scheme, for raising the numbers. Men aged 18 to 40 were informed that under the scheme they could continue to enlist voluntarily or attest with an obligation to come if called up later on. The War Office notified the public that voluntary enlistment would soon cease and that the last day of registration would be 15 December 1915.
Attestation
Men who attested under the Derby Scheme, who were accepted for service and chose to defer it were classified as being in "Class A". Those who agreed tio immediate service were "Class B". The Class A men were paid a day's army pay for the day they attested; were given a grey armband with a red crown as a sign that they had so volunteered; were officially transferred into Section B Army Reserve; and were sent back to their homes and jobs until they were called up.
Groups
The men who attested under the Derby Scheme were classified into married and single status and into 23 groups according to their age.
| Status | Year of birth | Group |
| Single | 1897 | 1 |
| 1896 | 2 | |
| 1895 | 3 | |
| 1894 | 4 | |
| 1893 | 5 | |
| 1892 | 6 | |
| 1891 | 7 | |
| 1890 | 8 | |
| 1889 | 9 | |
| 1888 | 10 | |
| 1887 | 11 | |
| 1886 | 12 | |
| 1885 | 13 | |
| 1884 | 14 | |
| 1883 | 15 | |
| 1882 | 16 | |
| 1881 | 17 | |
| 1880 | 18 | |
| 1879 | 19 | |
| 1878 | 20 | |
| 1877 | 21 | |
| 1876 | 22 | |
| 1875 | 23 | |
| Married | 1897 | 24 |
| 1896 | 25 | |
| 1895 | 26 | |
| 1894 | 27 | |
| 1893 | 28 | |
| 1892 | 29 | |
| 1891 | 30 | |
| 1890 | 31 | |
| 1889 | 32 | |
| 1888 | 33 | |
| 1887 | 34 | |
| 1886 | 35 | |
| 1885 | 36 | |
| 1884 | 37 | |
| 1883 | 38 | |
| 1882 | 39 | |
| 1881 | 40 | |
| 1880 | 41 | |
| 1879 | 42 | |
| 1878 | 43 | |
| 1877 | 44 | |
| 1876 | 45 | |
| 1875 | 46 | |
| Note: the Group numbers are not the same as the industrial classification numbers often seen in the man's service record. | ||
Mobilisation dates
| Group | Proclamation | Mobilisation |
| Mobilisation dates applying to those men who had chosen deferred service and were thus placed into Class A: | ||
| 1 | 25 Feb 1916 | 28 Mar 1916 |
| 2 | 20 Dec 1915 | 20 Jan 1916 |
| 3 | 20 Dec 1915 | 20 Jan 1916 |
| 4 | 20 Dec 1915 | 20 Jan 1916 |
| 5 | 20 Dec 1915 | 20 Jan 1916 |
| 6 | 8 Jan 1916 | 8 Feb 1916 |
| 7 | 8 Jan 1916 | 8 Feb 1916 |
| 8 | 8 Jan 1916 | 8 Feb 1916 |
| 9 | 8 Jan 1916 | 8 Feb 1916 |
| 10 | 30 Jan 1916 | 29 Feb 1916 |
| 11 | 30 Jan 1916 | 29 Feb 1916 |
| 12 | 30 Jan 1916 | 29 Feb 1916 |
| 13 | 30 Jan 1916 | 29 Feb 1916 |
| 14 | 16 Feb 1916 | 18 Mar 1916 |
| 15 | 16 Feb 1916 | 18 Mar 1916 |
| 16 | 16 Feb 1916 | 18 Mar 1916 |
| 17 | 16 Feb 1916 | 18 Mar 1916 |
| 18 | 16 Feb 1916 | 18 Mar 1916 |
| 19 | 16 Feb 1916 | 18 Mar 1916 |
| 20 | 16 Feb 1916 | 18 Mar 1916 |
| 21 | 16 Feb 1916 | 18 Mar 1916 |
| 22 | 16 Feb 1916 | 18 Mar 1916 |
| 23 | 16 Feb 1916 | 18 Mar 1916 |
| 24 | 13 May 1916 | 13 Jun 1916 |
| 25 | 7 Mar 1916 | 7 Apr 1916 |
| 26 | 7 Mar 1916 | 7 Apr 1916 |
| 27 | 7 Mar 1916 | 7 Apr 1916 |
| 28 | 7 Mar 1916 | 7 Apr 1916 |
| 29 | 7 Mar 1916 | 7 Apr 1916 |
| 30 | 7 Mar 1916 | 7 Apr 1916 |
| 31 | 7 Mar 1916 | 7 Apr 1916 |
| 32 | 7 Mar 1916 | 7 Apr 1916 |
| 33 | 27 Apr 1916 | 29 May 1916 |
| 34 | 27 Apr 1916 | 29 May 1916 |
| 35 | 27 Apr 1916 | 29 May 1916 |
| 36 | 27 Apr 1916 | 29 May 1916 |
| 37 | 27 Apr 1916 | 29 May 1916 |
| 38 | 27 Apr 1916 | 29 May 1916 |
| 39 | 27 Apr 1916 | 29 May 1916 |
| 40 | 27 Apr 1916 | 29 May 1916 |
| 41 | 27 Apr 1916 | 29 May 1916 |
| 42 | 13 May 1916 | 13 Jun 1916 |
| 43 | 13 May 1916 | 13 Jun 1916 |
| 44 | 13 May 1916 | 13 Jun 1916 |
| 45 | 13 May 1916 | 13 Jun 1916 |
| 46 | 13 May 1916 | 13 Jun 1916 |
| Note: many men were called up on dates later than that on which their Group was first mobilised. Those men who attested later than the Group mobilisation were given a month's notice of call-up. Many also chose to appeal for even later call-up: their cases were referred to local tribunals. | ||
Scheme seen as a failure
215,000 men enlisted while the scheme was on and another 2,185,000 attested for deferredr enlistment - but 38% of single men and 54% of marrieds who were not in "starred" jobs had still avoided this form of recruitment. Their reticence did much to hasten a move to full conscription. Voluntary attestation reopened on 10 January 1916, while the government considered the position.
Call up under the Derby Scheme began: Groups 2 to 5 were called up in the last two weeks of January 1916, and Groups 6 to 13 in February. The last single groups other than the 18 year-olds were called up in March. This last batch were called up in parallel to the first men to be summoned under conscription under the Military Service Act. Attestation under the scheme ceased on 1 March 1916. The recruits were not necessarily posted to their local regiments and from this time one it is not wise to assume that a man would go into his local regiment. Group Scheme recruits rarely had a say in the regiment to which they were assigned.
An extension to the scheme
On 6 September 1916 a start was made in posting notices announcing the formation of a new "Group B". This was to be open for voluntary attestation of those born in 1899, with the assurance that they would not be called for service until they reached 18. At the same time all men in "Group A" and those in "Class A" and who were born in 1898 were informed that they would be required to serve from the age of 18 years and 7 months (previously 18 and 8 months). This category of man began to be mobilised from 7 October 1916.