"Proper English" i.e. Received Pronunciation is not a high dialect. It was not used in court or government before the development of modern English some 700 years ago. Before then, that role was filled by French, thanks to the Norman conquest - so the need for a high-low distinction never developed in English to its typical extent.

In general, English in England does not display the variety of dialect found in mainland Europe or elsewhere in the world. Despite a variety of accent, it is overwhelmingly homogeneous in grammar and vocabulary (outside of slang).

There is no equivalent for English to the difference between Hoch- and Plattdeutsch, or between Tuscan Italian and its other variants - in both of these cases, the overwhelming part of the population learns both their local low dialect and the high dialect as distinct "languages".