There is a Mary Jane Bell aged 9 in the 1851 census for County Durham. She is one of 7 children of Yorkshire-born coal miner Matthew and Mary Bell. Her birth place is given as 'Isle of Man'. All the rest are born Yorkshire or Durham. With them is 12 year old house servant Mary Ann Dowson from Yorkshire. I can post the details, unless this is where you got the 'born in the Isle of Man' information in the first place. The family, without Mary Jane of course, seem to be in Westmorland in 1841, where Matthew is a lead miner.