Sidkeong Namgyal Tulku was a colourful figure in the history of Sikkim. This crown prince was an incarnated lama as well as a student at Oxford, and a member of the Royal Asiatic Society. This article considers the various roles of Sidkeong Tulku in the light of a Tibetan work by his hand, which has been previously not connected to his person. Written in 1909, it consists of ‘monastic guidelines’ (bCa’ yig) which are a clear witness to the time and circumstances they were written in. This traditionally framed work, authored by a supposed Buddhist modernist, addresses the education of monks, monastic economy, sex, and preaching to the laity. These guidelines shed light on the changing status of the monastery in Sikkim, in the midst of reforms and threats to Sikkimese sovereignty. In this article I examine the contents of these guidelines in the context of its author's eventful but short life, against the political, religious and social backdrop of a Buddhist kingdom in turmoil.