| Regimental number | 4131 |
| Place of birth | Esk, Queensland |
| School | State School, Queensland |
| Other training | Team driver |
| Religion | Roman Catholic |
| Occupation | Labourer |
| Address | Ottaba via Esk, Queensland |
| Marital status | Single |
| Age at embarkation | 25 |
| Next of kin | Father, W P Biffen, Ottaba via Esk, Queensland |
| Enlistment date | |
| Date of enlistment from Nominal Roll | |
| Rank on enlistment | Private |
| Unit name | 15th Battalion, 13th Reinforcement |
| AWM Embarkation Roll number | 23/32/2 |
| Embarkation details | Unit embarked from Brisbane, Queensland, on board HMAT A55 Kyarra on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 47th Battalion |
| Fate | Died of wounds |
| Place of death or wounding | France |
| Date of death | |
| Age at death | 28 |
| Place of burial | Puchevillers British Cemetery (Plot II, Row E, Grave No. 32), France |
| Panel number, Roll of Honour, Australian War Memorial | 143 |
| Miscellaneous information from cemetery records | Name recorded on War Graves Records as William Sydney Leo BIFFEN |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |
| Miscellaneous details | Name recorded on Embarkation Roll as William Sidney Lee BIFFEN |