Although Bowlby had retired from the Tavistock Clinic, this gave him more time to write and he went on to publish his definitional trilogy on attachment: Attachment (1969), Separation (1973) and Loss (1980). These were hugely influential and brought global attention to what the Tavistock Clinic was doing.
Bowlby’s work on attachment remains absolutely foundational to how we now understand child development and the formation of human relationships.