First of all, did you find this woman on the census? I searched both the 1841 and 1851 censuses across the UK for anyone with the stated birthplace of either 'Jersey', 'Channel Isles' or 'Channel Islands' but didn't come across anyone called Ann or Richard Milner. There is someone called Anne E.M. Milner living in Jersey on the 1851 census, but her birthplace is given as England.
Furthermore, you state that you want pre-1951 information- did you mean to say that Ann Milner was born about 1920 instead of 1820? Or did you mean to say that you wanted pre-1851 information rather than pre-1951?