LONDON — Almost anything linked to Winston Churchill can be collectible, right down to the butts of his cigars. But it is hard to imagine an artifact rarer or more intimate than the one scheduled to be auctioned on March 12: a vial of his blood.

The sample, long since turned from red to amber, was collected in 1962 by Patricia Fitzgibbon, a student nurse at Middlesex Hospital in London, where Churchill was being treated for a hip injury. The vial was supposed to be discarded after his stay, but Ms. Fitzgibbon got permission to keep it as a souvenir, according to a statement by Duke’s Auctioneers, which is organizing the sale.

Ms. Fitzgibbon kept the glass vial, which is seven centimeters, or 2 ¾ inches, long and labeled “Sir Winston S. Churchill W.W.B.9” in black ink, until shortly before her death, when she entrusted it to a friend. The friend decided to sell it this year, the 50th anniversary of Churchill’s death.

The auction house said it has already attracted interest from private collectors. The question is how to put a price on it.