Unique Value Count in 3 Columns Using Search Criteria

[sbenbow]

Hi All,

I've managed to do most of the above without any search functions, but
am getting stuck when trying to filter them by a specific value.

I'd like to do this via formulas rather than any external add-ins o
VBA.

An outline of the data:

A1-A10
John, John, Bob, Bob, Bob, Fred, Fred, Fred, Fred, George
B1-B10
Smith, Smith, Smith, Smith, Smith, Doe, Doe, Doe, Doe, Doe,
C1-C10
Red, Red, Red, Blue, Blue, Red, Red, Red, Blue, Blue,

I want to count the unique values, filtering on the info in C1-C10. E
I'd like to know the number of unique entries that have "Red" in C1-C1
(Answer = John Smith Red, Bob Smith Red, Fred Doe Red = 3)

To do this without filtering (eg counting all "Red" and "Blue
occurances), I have used the array formula
=SUM(1/MMULT(--(A1:A10&";"&B1:B10&";"&C1:C10=TRANSPOSE(A1:A10&";"&B1:B10&";"&C1:C10)),ROW(A1:A10)^0))

Does anyone have any funky forumlas that I can use to help count th
unique values whilst also having a filter? (n.b. the filter can b
manually entered in a cell - eg D1 can have the value "Red" in it)?

Thanks for any and all help!!