Hello Jan,
Delighted to hear from you.
Certainly there was a "Parkhurst Boy", Edward CARTER, born c1829, tried at the Old Bailey, London, on 02/03/1840 and sentenced to transportation for 7 years. He arrived in Auckland aboard the St. George in November 1842
However, I may have to disappoint you, because you mention the 1841 England Census and unless this related to the specific return made by Parkhurst Prison then it will not be the same Edward CARTER. I have a reasonable amount of information that I can happily let you have if your GGGGrand Uncle does prove a match though.
For the moment,
Tony