They did - or the United Kingdom did. Ireland had a rebellion in 1848 led by the Young Ireland movement. The Young Irelanders were inspired by republicanism in Europe and sought to break Ireland away from the UK. It was a short lived rising that took place in July 1848 in the village of Ballingarry, in Tipperary.

William Smith O'Brien thought that they could have a bloodless revolt by getting the Irish tenants to protest against British rule. This was during the height of the Irish Famine and death and devastation filled the countryside. Consequently, the Young Irelanders were not as organised as a future leader Parnell, in arranging a country wide boycott but that is where the initial intentions lay. But the British authorities forced the issue by declaring a suspension of habeas corpus. This would mean that the Young Irelanders could be arrested without trail and a decision was made to go for outright rebellion.

In spite of the failure and put down by the authorities the 1848 rebellion had far reaching implications for Ireland 's future. The leaders, James Stephens and John O'Mahony, would go on to form the Fenian Brotherhood or Irish Republication Brotherhood, the IRB. The IRB led other rebellions and eventually became the main body to lead the 1916 Rising in Dublin and become, with other paramilitaries, the Irish Republican Army or IRA. This Rising would ultimately result in the initial breakup of the United Kingdom in 1921 as the Irish Free State [now the Republic of Ireland] would leave the UK.

That is a good question and indeed one with which modern British political and social history has been regularly engaged with. As you might have guessed, this is a complicated issue (as always in history and any human matters) and I will warn you that there is no definite and final answer to this question. However I will give you a rundown of 1848 and some common explanations for British stability.

Almost no history of modern Britain and most certainly no history of Victorian Britain (1837–1901)^1 gets away without a chapter or two on the topic of Britain's "lack of revolution" and her supposedly peaceful way from constitutional monarchy to mass democracy. François Bédarida in his Social History of England 1851–1990 asks "Was Britain revolution-proof?", the German historian Bernd Weisbrod proposes an English^2 Sonderweg ("special path" – a concept from modern German history actually) into the modern. Book titles like Peaceable Kingdom. Stability and Change in Modern Britain (Brian Harrison, 1982) are telling. But not only historians noticed the British paradigm, contemporary observers did so too. George Bernard Shaw, a member of the Fabian Society, a socialist think tank, wrote in 1889 that Britain didn't need a violent revolution, no bloodshed, no execeutions "or anything else that is supposed to be essentially un-English."^3 Marx and Engels, frequent observers of Modern Britain (both lived in exile in Britain), started off in the 1840s expecting that Britain as the first industrial nation would naturally also be the first to experience a proletarian revolution. Engels actually predicted the revolution's imminence in 1846. Twelve years later however, in 1858, he wrote to Marx of the English as the "most bourgeois of all nations,"^4 whose working class had became bourgeois just like their aristocracy did before, complaining that maybe English workers were just too well off. Something had happened in between those years.

You mention the year 1848, so I gather that you are familiar with its significance as a "revolution year": The toppling of the restored Bourbon monarchy and the proclamation of the Second Republic in France in February, the March revolution in the German states, the revolutions in several Italian states, the Austrian and Hungarian revolutions et al. (1848 is most commonly paired with 1849 as the "European revolution years".) As a matter of fact, Britain did not slumber 1848/1849 away, for Britain they mark the end of what is sometimes called the two tumultuous decades of the 1830s and 1840s, they mark the end of the Early Victorian and the transition to the Mid-Victorian Era (or "High Victorian"). While the British industrialization was in full swing by the 1830s, socially this period was characterized by upheaval. Between 1839 and 1848 there were more arrests for "seditious activities" than in any other decade of the 19th century. There were several major riots in that time – among them the Newport Rising of 1839, the last armed uprising Great Britain has experienced –, many of them tied to the social injustices of early capitalism, of technological and structural changes. (E.g. the Luddite uprising 1811–1814, the Captain Swing riots of 1830.) The 1830s also saw the rise of Britain's (and arguably Europe's) first major labour movement: Chartism. There is some debate about Chartism's classification as a labour movement, I don't want to delve deeper into this now, but at the very least it is Britain's first concerted, formalized political movement which included the new urban working class. Chartism has at times being classified as a proto-socialist movement (most famously by contemporary Engels) but modern historiography has generally moved past this. The Chartist political agenda – the People's Charter of 1838, from which the movement got its name – with its main demands being universal male suffrage, the secret ballot and abolition of minimum property requirements for parliament membership et al. stands more in a radical democratic than a social revolutionary tradition. Most importantly, Chartist agenda had common ground with and sympathizers in at least the progressive parts of the Liberal Party. It also in a way took up the direction of the Reform Act of 1832, in which the at the time Liberal-dominated House of Commons had extended the electorate for the first time in British history, enfranchising essentially the upper middle class but still excluding the vast majority of the population. Still, Chartism was the last political mass movement of Britain that did not explicitly exclude proponents of violent revolution, although the proponents of "moral force" (non-violent protest to push the agenda in parliament) were always in majority compared to those of "physical force".

The heydays of Chartism were the years 1839, 1842, and 1848 (not coincidentally years of economic depression) were Chartist gatherings attracted hundreds of thousands of attendees. The largest of those actually took place on April 10, 1848, on the Kennington Common in London (Kennington Park today). Between 100,000 and 150,000 people attended the demonstration, the crowd was about to march on parliament to submit a petition with 2 million subscribers to the Houses. (An earlier petition attempt had failed because parliament refused to consider or even hear it.) Remember, this is 1848, not just any year. Two months ago a popular uprising in Paris had toppled the King of France - an event celebrated by the Chartist press –, one month ago the German masses had taken it to the streets. The city was gripped by revolution scare and the authorities decided to put up a real show of force. 8000 regulars with artillery were positioned near parliament. 22 000 policemen and a large force of voluntary auxiliaries recruited from London's "patriots" were gathered to contain the Chartists' march and restrict them to certain areas of the city. In the light of this, the Chartists abandoned their plans for a march, chose to send a representative to submit their petition (which, again, was ignored by parliament), and ended the protest prematurely. The whole fuss was over by afternoon.

to be continued

^1 British history is usually divided into periods identified by the ruling monarch. Accordingly, the Victorian Age covers the timespan of Queen Victoria's reign (1837–1901). However, especially the Victorian Age has become a label attached to a certain set of values, certain socioeconomic conditions, a certain Zeitgeist if you will, which in turn have become almost synonymous with 19th century Britain in general. Reflecting the actual popular usage of "Victorian" I will use the term quite liberally here as well.

^2 When German historians of Britain like Weisbrod or Niedhart use "England", they usually mean Britain. I know it's not fair but this pars pro toto happens a lot in German language sources.

^3 Shaw, George Bernard: "The Transition to Social Democracy." In Fabian Essays in Socialism, ed. G. B. Shaw, p. 200. London 1889.

^4 Engels to Marx, October 7, 1858.