Load profiles play an important role in electricity industry. They are widely used in tariff design and system operation planning. In the UK, the load profiles currently used by the industry were developed in 1990s. Although they have served the industry well for decades, the increasing number of low carbon customers may cause the actual load profiles to deviate from the original benchmarks. Thus, these existing load profiles may not be able to appropriately reflect the energy usage patterns nowadays. Therefore, it is necessary to test the accuracy and applicability of the existing classic load profiles and further refine them to better mimic the actual power consumption patterns. Theoretically, it is more accurate to obtain load profiles by measuring the power consumption of all customers in each class; however, the reality is that it is often too expensive or impractical to collect and analyze the load data for an entire area. This report proposes a power synthesis approach to testify and analyze the representativeness of the existing load profiles in the new power environment. The load profiles currently used by the UK's industry are first introduced and they are further tested with the recorded data taken from Dowlishford substation in Southwest England. Obtained results show that the current load profiles are out of date, and the corresponding errors are identified and the causes are analyzed.