Conversation so far:
Was was one of the 1990s icons?
The Spice Girls have been revered as the biggest pop phenomenon of the 1990s due to their international record sales, iconic symbolism and "omnipresence" in the late 1990s.
What other icons were there?
In 1999, a study conducted by the British Council found that the Spice Girls were the second-best-known Britons internationally--only behind then-Prime Minister Tony Blair-.
Did they receive any other labels?
CANNOTANSWER.
Are there any other interesting aspects about this article?
In 2006, ten years after the release of their debut single, the Spice Girls were voted the biggest cultural icons of the 1990s.

Question: Who conducted the study?
Self-contained rewrite: Who conducted the 1999 study that found the Spice Girls to be the second-best-known Briton internationally??