This article reflects upon ideas of tacit knowledge in order to examine the nature of planners’ expertise. It investigates the shifting knowledge and power dynamics between and within the public and private sectors, as a means of determining how tacit expertise is transferred and re‐appropriated in new domains and geographies of practice. Tacit understanding of what facilitates successful permissions and what impedes the approval process, helps planners navigate the plan‐led system and avoid inertia. Findings are two‐fold. Firstly, public sector planners transfer their own expert tacit knowledge to influence and direct local development planning. Secondly, the findings illustrate that public sector planners feel their tacit expertise is increasingly undervalued and traditional networks of knowledge transference have been dismantled due to the erosion of networks of peer support. This results in a disruptive counter narrative based in private planning practice where public sector experts are re‐emerging in commercial practice due to a range of factors, including: budgets cuts; demoralisation; and seeking greater job security in the private sector. This leads to new geographies of tacit knowledge, as local government planners transfer their knowledge into new professional environments. This can result in reconfigurations of locally embedded knowledge as expertise is repurposed and used to bolster the likelihood of development applications succeeding, often for profit motives rather than the broader public good. Furthermore, it can also lead to local knowledge being uprooted and spatially diffused across wider geographies as private sector planners frequently work across broader domains of practice than public sector counterparts. In conclusion, we outline gaps in our current understanding of the evolution of planning practice and outline future research opportunities.