Given the following reasoning and answer, what was the question? The relevant information is: It became fashionable in Britain during the Regency period, having been made respectable by the endorsement of Dorothea Lieven, wife of the Russian ambassador.
The answer: during the Regency period
The question Passage: It became fashionable in Britain during the Regency period, having been made respectable by the endorsement of Dorothea Lieven, wife of the Russian ambassador. Diarist Thomas Raikes later recounted that "No event ever produced so great a sensation in English society as the introduction of the waltz in 1813". In the same year, a sardonic tribute to the dance by Lord Byron was anonymously published (written the previous autumn). Influential dance master and author of instruction manuals, Thomas Wilson published A Description of the Correct Method of Waltzing in 1816. Almack's, the most exclusive club in London, permitted the waltz though the entry in the Oxford English Dictionary shows that it was considered "riotous and indecent" as late as 1825. Ann Bronte in' The Tenant of Wildfell Hall' has a scene set in 1827 where the local vicar Reverend Milward tolerates quadrilles and country dances but intervenes decisively when a waltz is called for, declaring "No, no, I do n't allow that! Come, it's time to be going home".

Question: Based on this passage, when did the waltz become popular in england?