Source: Michael Doyle Their Name Liveth For Evermore: The Great War Roll of Honour for Leicestershire and Rutland.
He was the son of Thomas Allen a Railway Station Master, born 1861 at Meppershall, Bedfordshire and his wife Mary Elizabeth, born 1862 in Southill, Bedfordshire. Kenneth James was born in 1899 at Bardon Hill, Leicestershire, his siblings were Winifred Mary, born 1862, Elsie Farr, born 1890 and Beatrice Maud, born 1891, all his siblings were born in Irchester, Northamptonshire, in 1911 the family home was at Bardon Station, Bardon Hill, Leicestershire.

Source: Leicestershire War Memorials Project.
The following information was kindly submitted to the project by F Tilley in 2016: "Kenneth James Allen was born in Bardon Hill, Leics his No was G.S.75802 Kenneth's records show he was formerly with the Warwickshire Yorks Regiment under the number 59783 He was also formerly registered as Tr/5/88042, 6th TR.Battn His dad Thomas (1861-1939) born in Meppershall, Bedfordshire His Mum Mary Elizabeth nee Farr (1861-1939)born in Southill, Bedfordshire."