Thanks for the reply, i did not know you could do that with scotlands people, appreciate the tip!
I didn't think it looked like William either, especially when comparing it to how William was written in the groom column....i agree that it definitely could be John, i was thinking perhaps Peter could be a possibility??
I have found one other record for a William Henderson in Mearns, Renfrewshire, on the 1871 census....right age, listed as living with a Janet Henderson, aged 73 annuitant, a daughter Sarah Henderson 28, a grandaughter Mary 27 and William which appears to be Wm is listed as a lodger...(i will attach that as well) I suppose that would make sense if his father was dec'd - perhaps he went to live with extended family.