Gratitude may help Universities to sustain relationships with alumni and stimulate valuable input into current students' learning experiences. This small-scale, qualitative study draws from the voices of alumni associated with a UK University. The study explores gratitude's role within alumni's reflections on Higher Education. We find that alumni's feelings of gratitude appear to resonate most clearly towards academic teaching staff. Despite these feelings of gratitude, there are few verbal expressions of gratitude from alumni towards academics. Indeed, alumni have a variety of concerns about saying thank-you to academics including feeling awkward and may even see saying thank-you as a sign of weakness. However, hidden expressions of gratitude are evident. Alumni engage in behaviour which benefits the institution and are prepared to do more if asked, especially by key academic staff. We suggest that it is useful to think of expressions of gratitude as known and unknown. The inequity between feelings of gratitude and known expressions of gratitude may mean that Universities and academics remain less alert to the evidence and potency of gratitude within Higher Education than reality would merit. Indeed, we argue that gratitude is a central idea with the ability to inform HEIs' alumni engagement strategies.