From pages 172-3, Sea of Faith (1984) by Don Cupitt:
There is one rather puzzling early example of knowledge of Indian religion. John Toland (1670-1722), an eccentric freelance Anglo-Irish writer and pamphleteer, was a man known to Leibniz. A theological radical, he was the inventor of the word ‘pantheism’, and in quoting precedents for this idea he mentions ‘the Brahminical theology’. Where Toland learnt this, I do not know. It is usually said that the first translations of Indian sacred texts into European languages came much later: Charles Wilke’s version of the Gita(1785), Sir William Jones’s Shakuntala (1789) and The Laws of Manu (1794) and […] Peron’s translation of some fifty of the Upsanisads(1802).”
Intriguing. But even if texts were not available in European languages, there were certainly people from the Indian subcontinent in London, notably Lascars serving on ships from India. He had also spent time in Holland which also had links with East Indies. Might Toland have learned this though word of mouth?