The 1753 to 1812 Colchester transcription CDs arrived, which have given some interesting info.
It's taken me back to my Pritchetts and I think I've identified another sister (Catherine) and possibly *another*, Louisa, as well as more marriages for the girls (one of them, Charlotte, married 3 times!). I've been trying to trace these women forwards in the records because if I can get them to the 1841 census or - even better - 1851, it would give me a clue where I could look for their baptisms/births. But as yet, I've hit brick walls with all of them.
Harriet Pritchett, married Joseph Clark White in 1801 in Lexden. He was buried in Lexden ("of St Botolph's") in 1806, and in 1807, Harriet married Benjamin Hudson. They're both of St Botolph's, but there's no Hudsons I can find that could be them.
Catherine Pritchett married Robert Ferguson in 1808, both of St Botolph's. He dies (not found his burial in Colchester or on FreeREG or Findmypast, and haven't found any children), and in 1814 she marries Benjamin Humphries of Weeley. Then they both disappear! (no Humphries in Weeley, nothing in the newspapers....).
I did wonder if Robert Ferguson was a soldier. It doesn't say so in the marriage register and they often did say so at the time, but of course, there's always some that are exceptions.
Another possible Pritchett sister is Louisa - she turns up witnessing Harriett's 2nd marriage and Charlotte's 3rd (in Fulham) as Louisa Lyons. Also witnessing Charlotte's marriage is Sarah Louisa Lyons, and I found a baptism at All Saints in Colchester in 1807 for Sarah Louisa, daughter of Wm & Louisa Lyons, born in 1802. I then found the marriage for Wm & Louisa in Canterbury in 1800 - he's an ensign in the 20th regiment of foot, and she's a widow, Louisa McDowell, of Lexden in Colchester. In 1800, most of the Pritchetts were still living in Lexden, and without her maiden name (I looked *everywhere* for her first marriage) I can't discount the fact that she might be a sister.
So I moved on a bit with my Pritchetts, but ended up with more mysteries, as is ever the way....