It took place just after midnight on Tuesday (17/11), next to the side entrance of Reading Minster of St Mary Virgin Church, opposite St Mary’s Butts.
A woman aged in her thirties was approached and spoken to by an offender, who then sexually assaulted her.
The offender is described as a white man, aged in his forties with short dark brown hair and a spikey beard.
He was around 5ft tall and of a skinny build, and was dressed in blue jeans, a black jacket and brown bobble hat.
The victim did not sustain any injuries.
Investigating officer, Detective Sergeant Jon Morley, of Reading police station: “This was a distressing incident during which a woman in her thirties was sexually assaulted.
“I would like to appeal for any witnesses in relation to this incident to please help with our investigation.
“If you can help, please call Thames Valley Police on 101, quoting 43200380024. You can also report online, or call independent charity Crimestoppers for 100% anonymity on 0800 555 111.”