Well it depends on what you meant by posh names. If you mean names which come across as posh, then yes, names like
Matilda,
Harriet,
Araminta etc would probably fit that.
However if you mean names that real (and I mean REAL) posh British people use, then those names don't fit as well. I attend a very prestigious boarding school, there are plenty of posh students here - and by posh, I don't just mean rich - I mean offspring of upper-class people with titles like Duke/Duchess, Earl/Countess, Lord/Lady etc. Their names? Well they're either very traditional (
Edward,
James,
Charles,
Elizabeth,
Sarah,
Catherine), or very posh nickname type names (think along the lines of
Jonty,
Kit, Bunty, and Tiggy). 'Proper' posh people, most of the time, stick to solid, traditional names, just like the royal family do!
~Charley~
https://www.behindthename.com/pnl/184785