United Kingdom, like several other countries worldwide, adopted an ambitious target to reduce greenhouse gas emissions until 2050 by 80%, as compared to the emissions of 1990. Energy system models, that optimize the total system costs under emissions constraint, have been extensively used to derive transition pathways and investment strategies. While these transition pathways are optimal, given the costs and emissions dimensions, they may not be optimal if further dimensions, such as supply security or stakeholder preferences, are added. State-of-the-art research argues, therefore, that near-optimal transition pathways need to be explored as well. Building on existing static approaches, this conference paper introduces a dynamic energy system model D-EXPANSE. This model is used to analyze the cost-optimal and near-optimal transition pathways of the UK power system until 2050. The model shows that investment strategies, that are nearly optimal with respect to the total system costs, are at the same time poles apart in terms of technologies and temporal distribution of investment.