Software engineering skills are broad and varied, encompassing not only technical abilities, but cognitive and social dimensions as well. Previous research establishes soft skills as being central for software engineering, e.g., teamwork, communication, and problem solving, but the relationship between these skills and how higher education prepares future software engineers for the workplace is unclear. These programmes should teach students the soft skills required for their careers, but a better understanding of which skills are valued and taught is needed. The perceptions of undergraduate alumni about the value of soft skills and where they were developed are reported on in this preregistered study of computer science and psychology alumni (using the latter as a contrast group). Replicating previous conclusions, computer science alumni rated problem solving, communication, and teamwork as amongst the most important skills, but when examining where these skills originate from, problem solving was strongly associated with education, and teamwork was strongly linked with employment. Communication is weakly associated with education, with influence from employment sources too. Alumni working in security-related careers highlighted that organisational skills were important more so than for the alumni population more broadly. We make recommendations for prioritisation of skill development based on the skills reported by the alumni. We suggest potential ways to encourage learning opportunities that promote scenarios students will find familiar during their careers, better preparing students for the needs of the workplace.