Tangut script
Grinstead became interested in the Tangut script whilst working at the Department of Oriental Printed Books and Manuscripts at the British Museum (later part of the British Library). Although the British Museum did not possess many complete or nearly complete Tangut texts, it did hold about 6,000 fragments of printed and manuscript texts written in the Tangut script, mostly of a Buddhist nature, that had been collected by Aurel Stein from the Tangut fortress city of Khara-Khoto from 1913 to 1916. These fragments had been largely ignored by Tangutologists, but during the 1960s Grinstead published several brief articles about them in the British Museum Quarterly. One of his articles, in 1963, identified the first non-Buddhist Tangut manuscript from Stein's collection, a unique manuscript copy of a Tangut translation/adaptation of a Chinese work on military strategy ascribed to Zhuge Liang entitled "The General's Garden".