Clooney, 53, and his new wife Amal Alamuddin, got married in Venice last month, are having a private bash at the lavish Danesfield House, which overlooks the River Thames, reported Femalefirst.
"Amal has a lot of her family in the UK so it made sense for them to hold another bash here following last month's wedding," a source said,
However, it is not known who else will be attending the party in South East England as members of staff at the hotel have been told to remain tight-lipped.