i think hes taller than 5'9...
i met him twice a few weeks ago...( he recognised me :) )
I'm 5'7, and he crouched down for the picture, and still looked taller than me.
I think he's taller than 5'9, about 5'11?
I've only seen him once. At the time I wouldn't have guessed he was over 5ft 7.
5ft 11 is certainly a very tall estimate, he's shorter than me and I'm only 5ft 8: http://www.celebheights.com/s/Alfie-Allen-5065.html