unmarried mother

i have just found out an ancester was born to a "spinster" mother i am not sure how to trace the mothers family i only know the place of birth was brownlow hill i have tried to work out about how old she was around that time and i get no one come up! and whats also strange was on the certs i have and cencus,s he has a father by the same surname! he was born in 1819. can anyone point me in the right direction on this? it would be a great help, thank you.