Configure Replicator to be in Manual mode
1.Go to central administration on the corporate office server.
2.Click application management
3.Click manage map families
4.Click the appropriate map family
5.Change the schedule for the map family to �manually�
6.Go to central admin on the London office server
7.Go to Configure Web application and disable replication.
8.On London office go back to application management then Manage Map families
9.Delete the map family for the site collection you will restore on the London office