“London completely dominates the political, cultural and economic life of the U.K. to an extent rarely seen elsewhere. That imbalance has been an issue in the run-up to Thursday’s election.”
The problems with primate cities are hardly unique to London (see here resources for teaching about primate cities using the example of Mexico City). The lack of a balanced urban hierarchy that we would see in countries where the rank-size rule applies is a political problem as stated in this NPR podcast. This additional BBC article bemoans Britain’s lack of a true second city, arguing that London’s shadow looms too large for sustained national development outside of the primate city.