I have only just registered with Roots. I stumbled across your chat re Amelia Pedgrift / Whitehead. I am the Gt. Granddaughter of Joseph Whitehead b 1814 and Elizabeth Whitcombe and have been trying to solve the mystery of Amelia for the last 30 years! My Grandmother was Elizabeth Whitehead b 1863, who married Frederick John Clarke
As far as I can discover, it looks as though Amelia was a servant / lodger in Joseph Whitehead senior's household in 1841, when his son Joseph was 25. They married on Aug 10th 1841 and are listed as married in the Census of 1851, but I think this record suggests that she was handicapped in some way. There is no sign of her in the Census of 1861, but Joseph is described as married. His own son, Joseph was born in 1861, mother Elizabeth Whitcombe, who is later listed as 'Housekeeper'. I can't find a marriage for Joseph and Elizabeth, but in 1881 and 1891 , she is described as his 'wife'.
The suggestion that Amelia Whitehead went off to America, presumably after splitting from Joseph, would offer an answer, but I'm not convinced that it's the right one. I would be interested in any other info that you may have.