According to Hart's Annual Army List of 1860, there were only two Charles Steel's who were officers in the Army by that date (4 years after the end of the Crimean War). The first was Veterinary Surgeon Charles Steel of the 12th Regiment of Lancers . . . who is probably not your ancestor. The other was Captain Charles Steel of the 17th Lancers. Unfortunately, I did not include his name in my book, as he does not appear on the Muster Rolls for the Crimea or Medal rolls of the 17th Lancers as entitled to a Sebastopol Clasp. Despite there being no evidence of his presence in the Regimental documents, Hart's states that he "served in the Crimea from 29th July 1855" which would entitle him to a Medal with a Sebastopol Clasp. I can only conclude that his time in the Crimea may not have been as one of the 17th Lancers and he may have transferred to that unit after the war. I have composed an entry for the supplement to my book which will come out sometime in the future which includes his appointment and promotion dates as follow:
Steel, Cpt Charles, 17th L [HAL60 154]. Appt Ct by purch 06-14-50; prom to Lt by purch 10-13-54; prom to Cpt by purch 06-30-57; “served in the Crimea from 29 July 1855 [HAL60 154]. Ed. Note: Steel’s name does not appear on the Mstrs of the 17th L during the period stated in HAL, nor does his name appear on the MRs.
If his name is on the medal rolls, it will be in some other regiment. The only other explanation that offers itself is that the clasp was awarded at a later date.