The arrival of high-speed trains (HST) brings an unprecedented time-space shrinkage that could greatly enhance inter-city connectivity. Meanwhile, it offers a major opportunity to reshape uneven spatial-economic development. However, the existing literature has presented a mixed picture. Thus, considerable disagreement on the wider effects of HST remains. This research contributes to the debate with new empirical evidence on two inter-related scales, based on the experience of British InterCity 125/225 and UK/France comparative practice from the West Coast Main Line modernisation and the TGV-Nord. The thesis first demonstrates the quantitative evidence. Then it takes a planning standpoint in examining multi-level government intervention in seizing opportunities presented by HST during the transformation process. The research findings lead to two major conclusions. Firstly, nationally, HST has had demonstrable and varied effects on cities within 1 hour and 2 hours from London, thus helping to generate renewed economies, but this effect has not been automatic or universal. Within 1-hour distance, HST towns located further afield from London could benefit from exploiting both commuting and intrinsic economic strength in knowledge-intensive activities; while 2-hour HST accessibility could benefit mainly from exploiting knowledge-intensive economic functions. Beyond 2 hours, the effect appears weak. Regionally, major regional cities have been reinforced by a HST hub position, but the effects have not necessarily spread out into surrounding sub-regions. HST needs to be well-integrated with urban and regional transport networks, so a spatial-economic relationship between a regional centre and its hinterland could be fostered to produce and magnify the wider effects. Secondly, transport alone is not sufficient to determine the wider effects in reducing regional inequality. Complementary measures are indispensable. Five conditions are found and highlighted to be vital, namely national political economy, constitutional capacity, planning priority and resources, city type and economic trajectory, and leadership and governance
