Wilfred was born in Swindon, Wiltshire. He was the youngest son of William (-1920) and Hannah (-1928) Clappen of “Cotswold”, Hathaway Road, Southbourne, Bournemouth. Wilfred had two sisters; Sarah Kate (-1968) and Ethel Hannah (-1974), and one brother, Allen. The family also kept a servant, Sarah W.
He was educated at High School Swindon, Taunton School (1904 - 06), Dauntsey Agricultural School, Market Lavington (1907-9), and gained a Wilts C. C. Agricultural scholarship to study at Armstrong College (1910 - 14), where he received a BSc. in Agriculture. Following this, he became a Master in Agriculture at the North Eastern Country School, Barnard Castle.
Wilfred was commissioned into the Army in January 1915, and was gazetted Second Lieutenant in the Durham Light Infantry, 10th Battalion, on 17th March 1915. He went to serve in France in the same month
Wilfred was wounded in action on 16th September near Courcelette, and died of these wounds on 22nd September 1916 aged 24. His Commanding Officer wrote: "He is a great loss to me and the battalion generally. . . . We had made an attack in the morning of 16 Sept, which failed owing to heavy machine-gun fire, and during the afternoon I sent him to reorganize what men there were in our front line, and subsequently received a note from him stating he had been wounded, and requesting that another officer be sent to take his place. . . . I hear he has died of wounds, shot by a rifle or machine-gun bullet." A fellow officer of his battalion also wrote: "At Delville Wood his behaviour throughout was splendid. First of all a shell blew eight men to pieces near him and cut him slightly in the neck, but he didn't seem to turn a hair. About half an hour later a shell killed another officer and a sergeant-major, and blew Wilfrid head over heels. . . . I found him lying in an old German gun emplacement shot through the neck. After that I was kept busy until dusk. I went back to the gun emplacement afterwards, but Wilfrid was not there: they told me he had walked out with the help of two men."