A worker at the tractor pull in Great Eccleston suffered a broken nose and fractured eye socket after being punched in what police have called an unprovoked attack.
Blackpool man Dean Holt’s injuries were so bad he needed surgery, and officers think he may have been hit with a knuckleduster.
They have now released a picture of the 26-year-old alongside an appeal for information about the attack, which happened at around 10pm on Saturday, August 26.
It was carried out by an Asian man, around 6ft, aged 30 and 40, of broad build, the force said in a statement.
He was also wearing a white t-shirt with blood stains on it.
PC Ken Armstrong said: “This was a nasty, unprovoked attack on a man who was simply working at the event and hadn’t done anything wrong.
“Such was the extent of the victim’s injuries we think he was hit with a weapon such as a knuckleduster.
“As a result, he has required surgery and has had to have two metal plates inserted into his face.”