The SCSC Working Group on Safer Complex Systems presented the first version of its guidance document at SSS’25. Work has continued, concentrating on applying the existing guidance to possible projects to test its effectiveness and applicability. Surprises have arisen during the creation of the guidance and subsequent work which have led to changes in the guidance. This paper describes some of the surprises and draws out the additional light they throw on the specification, development and modification of complex, safety-critical systems.