Short answers, pulled from the story.
British English is the set of varieties of the English language native to the United Kingdom, especially Great Britain. The term can refer narrowly to English in England alone, or more broadly to the collective dialects across Scotland, Wales, and Northern Ireland taken together. Tom McArthur noted in the Oxford Guide to World English that the term shares the same ambiguities as the word British itself.
English is a West Germanic language that originated from Anglo-Frisian dialects brought to Britain by Germanic settlers from what is now northwest Germany and the northern Netherlands. It was later shaped by two major waves of invasion: Scandinavian settlers in the eighth and ninth centuries, and the Normans in the 11th century, who introduced Old Norman and eventually Anglo-Norman.
Received Pronunciation, also called the King's English, Oxford English, and BBC English, is a region-free accent used by around 2% of Britons. It developed from a mixture of Midlands and Southern dialects spoken in London during the early modern period and is frequently used as a model for teaching English to foreign learners.
Samuel Johnson published A Dictionary of the English Language in 1755, which was a landmark step in English-language spelling reform. The dictionary focused on standardising both speech and spelling and helped push written British English toward greater consistency.
Countries that are former British colonies or Commonwealth members generally follow British English, as do European Union institutions and the United Nations, which uses British English with Oxford spelling. Australia, Malta, New Zealand, Nigeria, South Africa, and South Asian countries use varieties based on British English. The UK government promotes English in more than 100 countries.
The BBC Voices project invited the public to submit examples of regional English still in use across the country. The University of Leeds, which received a £460,000 grant from the Arts and Humanities Research Council in May 2007 to study the material, concluded that "the English language is as diverse as ever, despite our increased mobility and constant exposure to other accents and dialects through TV and radio."