As for John being in prison in 1841,
I wonder if he was the Jonnie Postlethwaite,mentioned as blowing his bugle to call out his friends,he was an apprentice painter,and a member of the Sawrie family,a ring leader imprisoned for his part in the copper riots,could get interesting,
1840
to see further information ,you need to go to Wikepedia and Manx notebook,Francis I believe is the good person who has written a lot of the facts here,so without her permission I will say no more,you can read it yourself