Knowles left Boeing yesterday.
He starts on 1 February in a comms role at Williams Advanced Engineering. The firm is owned Williams Grand Prix Holdings and was set up by its F1 team in 2010 as a consultancy, a year after it developed a KERS system, which is now used beyond motorsport itself.
Boeing is currently interviewing for a successor. In the interim, Knowles' old role is being covered by Andy Lee, who has been with Boeing for nine years and is on a three-month secondment from its US defence business.
Lee is being supported by UK comms manager Katerina Giannini.
Boeing's UK corporate comms operation is supported by agency Luther Pendragon.
Knowles was taken on by Boeing in 2011, before which he worked for aerospace, defence and security trade body ADS.
Boeing employs more than 158,000 people globally and is headquartered in Chicago.
This story was updated on 25 January to clarify the position of Williams Advanced Engineering within its parent group.