Thames Valley Police have released an image of a man officers wish to speak to as they believe he may have vital information about an assault in Gerrards Cross.
Shortly after 10pm on 12 March, a passenger on the number 102 bus argued with the driver before sitting down.
As the passenger got off the bus on Oxford Road, they spat at the driver, a man in his forties, and hit him in the face before disembarking.
The victim did not require hospital treatment.
Investigating officer PC Jake Padgett said: “I am appealing to anybody who recognises this man to please get in touch with us as we believe he may have vital information about this assault.
“If you are the man pictured, please come forward as soon as possible.
“To contact us, call 101 or make a report on our website, quoting reference number 43240116650.
“Alternatively, you can provide information anonymously to independent charity Crimestoppers by calling 0800 555 111 or via its website.”