Buffer to XML problem

[Greg Keogh]

Folks, I can't convert to byte buffer to an XML document. The input buffer
contains a serialized string with a UTF8 BOM which starts like this:

EFBBBF3C3F786D6C2076657273696F6E3D22312E302220656E636F64696E673D227574662D38223F3E0D0A3C5573
[cut]
. . . < ? x m l   v e r s i o n = " 1 . 0 "   e n c o d i n g = " u t f - 8
" ? > . . < U s

So I do this:

string xml = Encoding.UTF8.GetString(buffer);
var doc = XDocument.Parse(xml);

However the Parse dies with "System.Xml.XmlException : Data at the root
level is invalid. Line 1, position 1."

What am I missing here?

Greg K