When looking at marriage date of her daughter (1186), her daughter was not born bef ca 1150 (more likely 1160) & therefor Constance herself was prob not born bef 1120 (maybe 1130).

Gramps ID S0432

References

    1. of England, Constance [I29555]
    2. Birth, of England, Constance [E39672]
    1. of England, Constance [I29555]
    2. Birth, of England, Constance [E39672]
    1. of England, Constance [I29555]
    2. Birth, of England, Constance [E39672]