You are right about it being Sgt Bentley of the 11th Hussars. The following is from the entry in my book, In Search of the Light Brigade, about him:
? Bentley, Sgt William, (863), 11th H (p135) Bn in 1816 at Kilnwick, near Driffield, Yorkshire. Enl 07-07-35 in Beverley. Prior Occ: Farmer. At Kilkenny 1st& 2nd Mstrs [54-1-1]. At sea 2ndMstr; at Devna 3rdMstr [54-2-3]. Sick abd ship 3rdMstr [54-3-3]. Remittance - 3/10/0 - to Mary Bentley [54-3-21] Rode in Charge;life saved by Lt Dunn who fought off some Russians who were attacking Sgt Bentley fr behind [Kn 36]; slight wound in action at Balaclava [KA].At Scut 1stMstr [55-2-3]. At Baidar 1stMstr 55-3-3]. Prom 12-26-55 to TSM vice Joseph [55-4-2, 3]. Dc 07-08-60 in Birmingham. W/ Svc Trps entire period [54-1 to 56-1]. Medal [389/396] w/ B , I [389/396], & S  Clasps; not on Alma Roll [AS]. Att FBB 10-25-75 [ILN 10-30-75 442]. Member BCS 1877 & 1879 [as Sgt J. Bently][GM 39]. Signed Loyal Address of 1887. Died 03-01-91 at 2, The Crescent Groves, Yorkshire. Buried 03-05-91 in York Cemetery. Tombstone inscription reads “In loving memory of Elizabeth the beloved wife of William Bentley who died June 24, 1858, aged 33 years. Thy will be done. Also of the above William Bentley, late T. Sergt Major, 11th Hussars And one of the Six Hundred at Balaklava 1854 who died March 1, 1891, aged 74.” [YCA].