First a couple of questions regarding the chassis numbers.
Is 25LK really S25LK, a 1925 Springfield Silver Ghost, or
is it LK25, a 1923 Silver Ghost of UK assembly?
Is 6TB really TB6, a 1914/15 Silver Ghost of UK assembly?
What sort of information are you looking for? Ownership history? Technical?
Regardless, you might try the following:
Contact the RREC (email to [email protected]) for possible chassis cards, build sheets, ownership history.