In light of the increasing political involvement of people in environmental policies, it is important to understand the influences of political orientation on environmental attitudes and environmental behaviours regarding local environmental policies and issues. This study investigated the differences in the levels of environmental attitude (EA) and environmentally responsible behaviour (ERB) among individuals of different political orientations, including rarely studied pro-centrists and people with no political orientation, through the case of country park development in Hong Kong. A household telephone survey was carried out, and 481 successful samples were collected. SPSS 24.0 was used for the statistical analysis of the collected data. The results of the current study showed that individuals with no political orientation and a pro-centrism stance represent up to 60% of the population in Hong Kong. Liberals reported the highest levels of EA and ERB, followed by the intermediate groups of pro-centrists and individuals with no political orientation. Conservatives were found to be least concerned about the environment and least involved in ERB. Thus, a gradual decrease in EA and ERB from liberals to conservatives was observed. A discrepancy between the levels of EA and ERB among all the participants was found. Reasons for such differences were suggested based on local societal atmosphere and attitudes towards ERBs that oppose the government.