Henry seems to have been convicted on 4 April 1848 for Larceny and sentenced to 4 months. He has a second conviction on 17 October 1848 for which he was sentenced to transportation which happened on 16 July 1851 (presumably on the next available ship). My guess a second offence so soon after being released was why he was sentenced to transportation.
Best wishes
Tony
(no relation to Henry so far as I am aware - my Dover family is from Oxfordshire)