It appears that there is a brown sub species of tawny owl.
http://en.wikipedia.org/wiki/Tawny_Owl
This article gives brown owl as a synonym of tawny owl.
http://www.birdcheck.co.uk/main/prev...iewpage345.htm
More pictures:
http://www.stevenround-birdphotograp...awny%20Owl.htm
Bill