I recently inherited an antique English wine cup that I want to
determine the value of (for insurance) and possibly sell. It was
purchased in 1946 for $2000 and is described as follows:

"A Charles I silver wine cup engraved with a Coat of Arms in plume
mantling and the inscription 'Ex Dono Thome Langley Armigori' on a
baluster stem and circular foot.  Maker's mark "A" in a lozenge,
London 1641.  Height 6 1/4 ins.  Weight 9 1/4 ozs.
 
The Arms are those of Langley, of Stanton, Co. York, and Higham
Gobion, Co. Bedford.
 
One of the finest examples that we have ever seen.  The condition and
form are exceedingly good."  So said Thomas Lumley Ltd, Works of Art,
3 Bury Street, St. James, London, S.W.1
 
What's it worth and who might be interested in buying it?

Your best bet is to ask major auction houses:  Sotheby's, Christie's,
Bonham's, to mention well known English ones, which also are active in
the States.

http://search.sothebys.com/

http://www.christies.com/home_page/home_page.asp

http://www.bonhams.com/

Of course, there are others, also US auction houses, but since the cup
is English, those people would be the ones closest to the market for
the cup.