Between 12.15am and 12.45am on Saturday 15 July, a 48-year-old man was assaulted by an unknown man in the Rockwood Pub in Kingsbury Square.
It is believed he was either punched or head-butted.
The assault caused him to fall backwards to the floor and hit his head on a radiator.
As a result, the victim sustained a broken jaw which required surgery.
He has now been discharged from hospital but is still suffering from discomfort as a result.
Investigating officers have now released an E-fit of a man they would like to speak to in connection with the incident.
He is believed to be a man in his twenties, with brown cropped hair and an earring. He was of a stocky build and was wearing a stripy t-shirt and jeans.
If you recognise the man in the image or witnessed the assault but have not yet spoken to police, please call PC Rachael Peddie from Force CID Aylesbury on 101, quoting incident reference 43170209531.
If you have any information relating to this case, please call 101 quoting reference '43170209531', or contact Crimestoppers anonymously.