Ms Street-Porter, who was previously responsible for youth TV on BBC and Channel 4, was heavily criticised after making her outspoken speech last month at the Edinburgh Television Festival.
She accused the "grey men" running television of stifling creativity and talent and bemoaned the "crisis" in the industry.
L!ve TV, a 24-hour mixture of pop videos, interviews and lifestyle items aimed at young people, was launched by Mirror Group in June and has so far failed to capture a significant share of the competitive cable market.
In her Edinburgh speech, Ms Street-Porter she said: "A terminal blight has hit the British TV industry nipping fun in the bud, stunting our growth and severely restricting our development.
"This blight is management - the dreaded four Ms: male, middle-class, middle-aged and mediocre."
The so-called M-people hit back, saying that Ms Street-Porter was over excited in her speech due to the fact that she had played to a bigger audience than L!ve TV had enjoyed since its inception.
There have been reports of disagreements between Ms Street-Porter and David Montgomery and Kelvin McKenzie, directors of Mirror Group TV. These were given added spice by the news that Mr McKenzie, former editor of the Sun, had secured exclusive rights for the Rugby League World Cup's early stages for L!ve TV while Ms Street-Porter was on holiday.
Stories about Ms Street-Porter's imminent demise have been circulating in the media since before her speech. Her office was last night said to have been cleared out although she was not due to return from holiday until today.
Always a controversial figure, Ms Street-Porter, 48, was disappointed when passed over for the controllers jobs on both BBC1and 2. She spent six years at the BBC where she was head of youth programming and independent commissioning.Reuse content