As of 1st October 2019, Southwark Safeguarding Adults Board have formally adopted the London-Wide Adult Safeguarding Policy and Procedures, including the data sharing agreement. These can be downloaded here.
The Southwark Safeguarding Adults Board agrees local procedures. Local Authorities must comply with duties under the Care Act (2014).
The Government provides information sharing advice and guidance for safeguarding practitioners, which can be found here.