Look at these.

Photos of a Tawny Owl chick with one parent - Kingsley 21.03.15 (by John Coe). This chick has appeared quite early for this species, which lay mainly during March with the eggs hatching 28-39 days. It is also notable for there being an only one as Tawny Owls typically produce 2 -3 eggs though a range of 1 - 5 is recorded http://blx1.bto.org/birdfacts/results/bob7610.htm. So maybe this pair only ever had one egg or other eggs or nestlings failed for some reason. Tawny owls are a single-brooded species, so once these parents have reared this youngster they can have a rest from childcare until next year!