I'm not sure what you would consider "mass?" What percentage of the general population have to be "poor" to constitute mass? Is that more than 50% of the people? A recent study by the Institute of Fiscal Studies found that 23.3% of the British population were in "relative poverty." Of course, now that we have a social safety net poverty also looks very different than it did in the past. However, when we do talk about the history of poverty in the 20th century, we do have to talk about the anomaly of the 1930s, which saw estimates as high as 40% of the population being in abject poverty (The Great Depression). Even today, there are estimates that between 15 to 18 percent of the population of England is in poverty (about 9 million people). Today though, the poor are distributed around the country, live in public subsidized housing, and have at least some economic support through poverty programs. It is the social safety net that allows poverty to not seems so horrific as it did in the two preceding centuries.

The biggest difference between 18th and 19th century poverty and poverty before industrialization is the slum. Poverty had always been with us, it just had been isolated in small pockets. And in a largely agrarian society with few people educated, poverty did not mean the same as it does to us today or to the Victorians. Most people, other than the disabled, could find enough to eat through manual labor in the 16th century and before. The slum was a creation of the immense movement of so many out of the countryside due to industrialization. This is the condition that give rise to the novels of Charles Dickens and our view of the poor of that time. Studies made by the government in the late 1800s, gave estimates of about 25% of the population living in poverty (not that far much off from modern estimates of up to 18%). And while, I can't find estimates for the early 1800s, I would bet that that percentage of the poor would have easily been above 35% in the 1830s and 40s.

Still, there were still slums in many urban areas as late as the 1970s in Britain. Consider this link to photographs of urban slums in the 1970s:http://www.dailymail.co.uk/news/article-2776842/Shocking-photos-capture-real-squalor-Britain-s-slums-poverty-meant-afford-Playstation.html . Sadly, we are seeing a reemergence of the slum. In Britain, a number of illegal "sheds with beds" housing areas have been set up these rent to largely the illegal immigrants. http://www.bbc.com/news/uk-17185294