Pearl - I have looked at the marriage cert. Although she 'married out', she was of full age, so would not have needed parental authority to marry. I can see no reason why she would intentionally tell the registrar that her father was called Jacob.
The father with whom she was recorded in three consecutive censuses only ever went by the name of Morris (in non-Jewish circles at least), so I can only draw the conclusion that there was a mistake. I would suggest starting a new topic on one of the general boards to solicit other opinions.
Would you consider ordering the birth cert of Sarah Muscovitz, Q1 1880 Mile End (1c, 554)? You could always specify that you only want the cert for a child of Morris and/or Elena/Eleanor.
Shaun - Naturalization did not confer any significant benefits for your average Polish/Russian Jew, and many did not bother. It was obviously different for German Jews (such as my great-grandfather) in the run up to WWI. In short, I don't know why they left it so late. The papers themselves may of course provide a clue.
You might want to join the mailing list of british-jewry.co.uk, and put the question to them.
Justin
PS I'll change my business cards accordingly.
