However, the deepening vernacularisation and the ensuing displacement of Latin and French was accompanied inevitably by wholesale importations from these languages into the vernacular in order to enable English to function in the new domains. As a result, the “overt” diglossia between lower registers (associated with the vernacular) and more elevated ones (dominated by French and Latin) was gradually transposed into “latent” (concealed) diglossia, with the hierarchical relations between registers now determined by the correlation or balance between the native Germanic and the foreign Romance elements within the vernacular itself.

The expansion of the range of functional uses of the vernacular continued throughout the seventeenth century and was driven by the rising interest in science and philosophy. Political pamphlets, journals, essays, and the first newspapers were now written and published in English. The foundation at that time of modern science brought about a revolution in thought and was accompanied by an immense expansion of the scientific vocabulary. Since Latin had been for centuries the universal language of science, it became the natural source from which scholars drew their new coinages for technical and scientific uses.

The Restoration was also a time of very close social, cultural and commercial relations with France. Charles II and his Court had lived there long, and the returned exiles brought back with them a new wave of French influence. It was especially significant in determining social manners and standards, ideas of conversation, and theories of poetry and resulted in a fresh influx of Gallicisms. Their functional status was quite distinct, as many of them were fashionable “social” terms at some stylistic remove from common usage. This stylistic distinctiveness effectively precluded their full assimilation in the language, and many of them still retain their French spelling and near-French pronunciation and continue to stand out against the background of the native English word-stock (e.g., rapport, doyen, penchant, dishabille, faux pas, nonchalance, cortege, ménage, tête-à-tête, and many other). 

By the first half of the eighteenth century vocabulary expansion had reached the stage when it was time to take stock of the accumulated word-hoard by recording, defining and, where possible, “fixing” the usage of the borrowed words. This task was accomplished successfully by Samuel Johnson and his famous Dictionary of the English Language (1755). By that time the Romance component of the English language had developed into a fully-fledged lexical layer, while the vocabulary of English as a whole had settled into the condition we know today. In the preface to his Dictionary Johnson offers his comments on the composite nature of English: 

This description applies to the present-day state of the language. As a result of the continued borrowing from the Romance sources over centuries, the Romance element now constitutes half of the total English vocabulary. The basic structure of the language, however, remains Germanic, with the native Germanic part of vocabulary serving as the basic register. It is against this neutral native background that the borrowed part has developed its specific stylistic resonance.