A must read piece from the Guardian:

Consummate actor that he was, Blair was skilful at concealing the
severity of the descent from the public and the media. He was also
adept at masking it from the great majority of his colleagues and
officials. "He managed to disguise it from most people," says his
Cabinet Secretary, Andrew Turnbull. "It wasn't visible to me. I only
believed in The Wobble when it became clear afterwards that there had
been one."

Only those closest to him could see the interior
collapse of the Prime Minister. There had been few days since 9/11 when
he had not been living on his nerves. He found it difficult to sleep.
When it eventually came, rest often did not last long. He would wake
with a start in the middle of the night to find sweat trickling down
the back of his neck.