Following this info on her profile by Private User:
=Leah Isaacs (nee Harris)'s marriage certificate dated 6 December 1837 says she was a Minor - which means she was under 21 at the time - so she was born AFTER 6 December 1816.
She is described on her marriage certificate as a minor, spinster, of 6 Elliston Street, Middlesex Street, daughter of Solomon Harris, General Dealer.
In the 1841 census (notoriously inaccurate for ages) she is 22 - at Harrow Alley, St Botolph Aldgate, London
In the 1851 census at 5 Harrow Alley she is 33, which would put her as born about 1818+
I am changing her birthdate to c 1818. Thanks for the research work, Private User.