Diglossia of the Ferguson 1959 type also implies non-genetic diglossia of the Fishman (1967) type, which then licenses linguistic diversity at the grass-roots level. Since diglossias typically reserve their concern 14 for purity and uniformity at the H level, but ignore the linguistic habits at the L level, an illusion of uniformity and purity is maintained, while L-variety diversity can be tolerant of all kinds of things. This system thus unites the well-known diversity-within-unity paradox that India is famous for: unity at the top (H), overt level, diversity at the unofficial L-variety level.
Note that the regulation of language here is a kind of language policy. It falls within the realm of what is called `corpus planning'--structural control of the H variety in order to control its accuracy. It is also an example of `status' planning, in that it regulates the status of the H variety, and not that of the L-variety. L-variety language remains unregulated in terms of its status and its corpus.
In my understanding of language policy, the regulation of the status and corpus of the H-variety is a prime example of overt policy, while the non-regulation of L-variety languages is an example of covert policy. It is not the case that there is no policy toward the L-varieties, but that de facto their status is purposefully unregulated. Both of these facts, the overt and the covert, are deeply rooted in Indian linguistic culture, I would hold. Both are part of the situation that persisted for centuries, perhaps millennia, as is clear from all the evidence we have from writing about language in the subcontinent.
Occasionally, however, the stability of this H/L dichotomy would be shaken by forces from within or from outside the society. An example of an `inside' force was that of Buddhism, which profited from the wide gap between the ritual forms of Sanskrit and the spoken vernacular by leaping into the breach and using the L-varieties as vehicles for the dissemination of Buddhism. This disturbed the system profoundly, led to a shake-down and abandonment of the exclusive dominance of Sanskrit, but still allowed diversity to flourish--Buddhist Hybrid Sanskrit, Pali, and other linguistic traditions arose; Tamil was already on the ascendant in the South--but without displacing Sanskrit from its niche. Diversity was preserved.
An outside challenge to India's linguistic culture came with the arrival of Islam and the introduction of Persian as the `official' language of the Mugal Empire. Needless to say, Persian may have claimed a domain in government, law, and commerce in Mugal India, but it never displaced any other variety from its domains. It did have an effect on spoken Hindustani resulting in the development of a literary language written in Perso-Arabic script (Urdu), but again no exclusive domain was claimed by Urdu except perhaps eventually to replace Persian in the scheme of things.
Even the arrival of European languages (chiefly Portuguese and then English) did not deeply disturb the equilibrium of Indian linguistic culture at first, (English replaced Persian) and even after Macaulay's famous minute and the development of English-style education, English was not thought of as displacing others, but as a variety that would allow the British better to govern India and bring it into the modern world. Most of the population of India was totally unaffected by English education, since they received no education at all, in any language. 15
Before Independence a kind of administrative and linguistic chaos, similar to the diversity of the Austro-Hungarian Empire, reigned all over India. Moslem rulers ruled over Hindus and Moslems; Hindu rajas ruled over Hindus and Moslems, and what languages they spoke was largely irrelevant (at this point there was neither cujus regio, ejus religio nor cujus regio, ejus lingua. It was not until the twentieth century that a large-scale linguistic census of India was undertaken (Grierson 1903-28) and then only in the northern parts of British India. 16
Perhaps the greatest challenge to Indian linguistic culture originating from the impulse of English was that English education, English rule and English-imposed modernization created expectations that had not existed before, and created domains (e.g. western professions, the postal and railroad system, the civil service) that were new, and with these domains, economic expectations that had hitherto not existed. As time went on it became clear that who would control these domains would crucially be linked to who controlled the language dominating them.