Studies of individual sound change over the lifespan benefit from availability of regular broadcast recordings by individuals whose role keeps them in the public eye over multiple decades. Annual Christmas (and other) broadcasts of the late Queen Elizabeth II have served to disentangle the impact of linguistic sound change on vowel quality from the natural effects of aging. In this paper we show that, in contrast to the well-documented changes in segmental vowel quality, key prosodic features of the late Queen’s broadcast speech in the public domain changed little over 70 years. Five speeches are analysed, ranging in broadcast date from 1947 to 2017. Each speech was segmented into intonation phrases based on auditory impression and each phrase coded for discourse structure. Values of maximum F0 per phrase show expected age-related decline over the lifespan, but linear regression models indicate minimal change across recordings in speech rate (sylls/sec), number of words and syllables per phrase, and duration of phrases and inter-phrase unfilled pauses; we ascribe the few observed differences to specific contextual factors (e.g. ill health or challenging content). Overall, we interpret this stability as a marker of individual performance style across the lifespan, within a restricted discourse genre.