Jennifer Arcuri
"Everyone could see the dramatic difference of this man when I entered the room."
Arcuri was given access to three foreign trade missions led by Boris Johnson.
The prime minister is facing a probe into whether he breached standards of public life in relation to the alleged affair.
The businesswoman also reportedly said she had been bombarded by the PM's "avalanches of passion".
Police watchdog decides against further action, but City Hall set to renew its own probe.
The IOPC has been assessing whether there are grounds to investigate the PM for misconduct in public office since September.
Prime minister has refused to discuss the nature of the personal relationship with ex-model amid allegations of an affair.
"What was the point of coming on TV if you're not going to say anything?" Lorraine asked shortly after the live GMB interview.
She described herself as "faithful, supportive, and a true confidante" of the now-prime minister.
But City Hall says it is “not able to publish it”.