The present article presents the most essential principles of the British constitution, namely its four most renowned principles: parliamentary sovereignty, the rule of law, a unitary state and a parliamentary government under a constitutional monarchy. As they have arisen over a centuries-long political process, their meanings and significance have caused controversy. Presenting them from the historical perspective provides a context for clarifying some of the myths that appear to have pervaded any discussion on the British constitution. The historical context and the division of the text into three major parts results from a view advocated by many theoreticians of the British state, who see its constitution as a product of the past cumulative experience rather than any definite political action. The article also attempts to explore the most important and contentious issues that have become focal points for current political discussion in the post-1997 reforms time, a period when the Labour party has introduced its reform agenda. It presents the first tangible outcomes of the introduced measures and their impact on the understanding of the traditional British constitution.