Allegedly Tony Blair told his friend Shirley Williams that Bush said this. Snopes claims this is false based on Alastair Campbell's [Blair’s director of communications and strategy] say-so. https://www.snopes.com/fact-check/french-lesson/
He says “I can tell you that the prime minister [Blair] never heard George Bush say that, and he certainly never told [his friend] Shirley Williams that President Bush did say it. If she put this in a speech, it must have been a joke.”
While Blair / Campbell have an obvious interest in denying this (it's not good to be rude about other countries leaders), we might reasonably be suspicious of Campbell's denial.
He says “I can tell you that the prime minister [Blair] never heard George Bush say that, and he certainly never told [his friend] Shirley Williams that President Bush did say it. If she put this in a speech, it must have been a joke.”
While Blair / Campbell have an obvious interest in denying this (it's not good to be rude about other countries leaders), we might reasonably be suspicious of Campbell's denial.