The Handwritten letters by Sir Winston Churchill are very hard to come by. I have found a gallery that has both typewritten and handwritten letters signed by Sir Winston Churhill. This link will take you to the one in particular that may interest you: http://www.kwrendell.com/full-description.aspx?ItemID=20402927 It is owned by the Kenneth W. Rendell, Inc. The specialize in Historical Documents, Autographs, and Manuscripts.
This is how to reach them:
Toll Free:(NNN) NNN-NNNN/p>
Fax: 212-717-1492There are other sites that do auctions on Signed Memoribillia, but this link I have given you specialize in this type of rare Memoribillia and Autographs.
Please let me know if you need further help. Joan