This article challenges the assumption that the early modern engineer acted as a reliable agent for colonial authorities. Far from acting as trusted mediators between colony and metropole, experts could exacerbate tensions. The English East India Company knew this, and avoided engineers throughout its early history. This article considers the interplay between authorities in London and their subordinates in Bombay. The company's directors saw engineers as untrustworthy agents who increased expenditure and disrupted the company's system of consultative governance. For much of its early modern history, the company's fortifications and built environments relied on a knowledge network of informal expertise. Examining these experts-in-context reveals how expertise was managed and built environments maintained in colonial settings. When the company did turn to experts in the mid-eighteenth century, it struggled to utilise and incorporate them. This demonstrates that in some colonial contexts experts could be profoundly disruptive.