Bidwell moves at the end of the year to become managing director of US clothing and lifestyle brand Anthropologie's European arm.
Visit London could not confirm or deny that outgoing chair Tamara Ingram would now be extending her stay until April (she was supposed to be ) to facilitate the hunt for a replacement.
Bidwell's position will be much sought after and The Visit London board meets in October to discuss his replacement.
"James has made a tremendous contribution to tourism in London. He guided the industry following the tragic bombings in July 2005 when tourism faced tough times," said Mayor of London Boris Johnson. "Visit London has flourished under his leadership into a multi-award winning agency that sets the industry standard for destination marketing."
Meanwhile speculation is also rife over Ingram's own position with former Excel London managing director of conferences and events, Vanessa Cotton, thought to be in the running.
London welcomes more overseas visitors than any other city. The capital's tourism industry is worth over £16 billion to the local economy and supports over 250,000 fulltime jobs.