At the end of several recent episodes of "Late Show with David
Letterman," announcer Alan Coulter gave flowers to the same woman on
stage. Who is this woman?

The woman is former soap opera actress Margaret Hall.

"Late Show with David Letterman (1993) TV Series 
(uncredited)... Red-Haired Lady Who Receives Flowers 
 From Alan At The End Of Each Show (2004-)"

Internet Movie Database: Margaret Hall
http://us.imdb.com/name/nm0355861/

"Every evening at the end of David Letterman's program, a lovely
red-haired mature lady walks onstage and a man comes on and hands her
a bouquet of long-stemmed roses. She smiles and waves to the audience.

Who is she? I guess she might be the mother of Dave's son?

-- Marion E., Walnut Creek

Dear Marion:

Definitely not little Harry's mum. The mysterious red-haired woman is
actress Margaret Hall. For the past year, she's been shown receiving a
bouquet of roses from 'Late Show' announcer Alan Kalter. Why? We have
no idea why.

Hall has been in a number of movies and television shows but may be
best known for playing Mayor Liz MacNamara on the ABC soap 'One Life
to Live,' 1991-1996."

Contra Costa Times: Joan's World
http://www.contracostatimes.com/mld/cctimes/entertainment/columnists/joan_morris/10597670.htm

"DEAR MARILYN & STACY: At the end of Late Night with David Letterman,
Alan (the announcer) presents a bouquet of flowers to a red-haired
woman who waves. Who is she and why was this added to the show?
 
Rose 
Providence, RI 
 
DEAR ROSE: We took your question to an executive at CBS, who noted
that the woman in question is an actress named Margaret Hall. As to
why she makes the nightly appearance, the response was, 'There's no
explanation for it. It's just one of the things that makes Late Night
so unique."
 
Cached copy of AIM Celebrity: ASK BECK/SMITH 
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Google search strategy:

Google Web Search: "david letterman"  "flowers to"
://www.google.com/search?hl=en&q=%22david+letterman%22++%22flowers+to%22

Google Web Search: "margaret hall" "david letterman"
://www.google.com/search?hl=en&q=%22margaret+hall%22+%22david+letterman%22

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Best regards,
pinkfreud