You might not be able to find a marriage between Henry and Alice because it may have been a clandestine marriage or a "fleet marriage." Which was held in secrecy, and many times without a church banns or marriage license. The marriage act of 1753 stopped this from happening frequently.
I find with many of my ancestor who lived before the 1750s have no marriage record. It makes finding a mother's maiden name or who a daughter marries very hard. If they have rare given name, like Frances, Priscilla, or Cornelia, I find baptism records that include a mother's name, and try to track the mother until they die. I usually go off of names, and it helps if someone else in the family also has a rare given name, as then her children may also have the same name. If a burial record with an age can be found, it's even better. Of course I doubt everyone is 100% correct.
