On Mon, 03 Sep 2007 07:51:30 -0700, Mr Thant wrote:

The best route from King's Cross to King's Cross Thameslink is via the
Victoria Line platforms. It's not directly signposted - you have to go
into the tube station and follow the signs to the Victoria Line, then
from there follow the Thameslink signs on the platforms,

IIRC the signs directing towards Thameslink start in the tube ticket
hall, at the top of the escalator to the Victoria Line.