After a tortuous late-night sitting on Tuesday evening, councillors rejected plans to add 56 rooms to the Mansion Wharf student accommodation block in a 5-storey extension.
Southwark planning sub-committee B resolved that the extension would be overbearing and have an unacceptable impact on residents of the neighbouring Orchard House.
Mansion Wharf, formerly Landale House, was originally a section house for police officers at the adjacent Rotherhithe Police Station.