I think you mean "coalition" and will avoid doing the joke about it. But, in short: Why would they have?

(Schematic summary incoming) In 1815, the Congress of Vienna reorganised european politics under the form of the "Concert of Nations" - five Great Powers were to dominate the continent: Great Britain, Austria, Russia, France, Prussia. Asides from them, there were a few "secondary powers" (think Spain, Sweden, the Netherlands), and a dust of small states like, say, Switzerland. What this basically meant was that the 5 GPs would try to solve their disagreements peacefully, through the "diplomacy of congresses", for instance, in order to "ensure peace"; that is, ensure order on the continent. No GP should be allowed by the others to go on a mad conquest spree like revolutionary France did; liberal, nationalist and revolutionary agitation would be kept carefully in check, and smaller nations would basically be told to keep quiet and let the five GPs take over the world. The arch-example of it was the 1823 intervention in Spain: when the absolute monarchy of Spain was taken down by an uprising inspired by the French Revolution, the Powers met in Congress, France asked permission to go restore the monarch, which was granted - and order was restored.

So, the situation was that only the GPs could have taken the initiative of such a confrontation. And why would they have jeopardised the whole situation, which was pretty nice for them, by doing so? Of course, the UK was the most powerful of them; but in European affairs, it wasn't much more than a primus inter pares, content to just prevent the emergence of a new continental hegemon while continental powers didn't bother too much with the oversea matters that made much of Britain's business at this point. And coalising against the UK would also have meant putting their own rivalries, which remained real and strong, asides: for instance, France rivaled Germany over the Rheinland, Russia and Austria were facing in the Balkans, etc. Indeed, a few times the continental powers took position together against the UK; but on its own side Britain was both aware of this possibility and content with they dominant position, so took care not to take any action too provocative. That is, the political "cost" of banding together to face the UK - troubling the very order they reigned upon, forgetting their rivalries, not to mention, well, facing the greatest world power - was way lower than the potential benefits they could have won from it - since Great Britain's domination wasn't too much of a pain; and they knew that the UK would just have been replaced by one of them anyway. In fact, it was this mecanism - making orderly peace more appealing than a hazardous confrontation to a select few GPs - that kept peace on the continent for a century; until, in 1914, Austria felt threatened to lose their GP position entirely, while more and more rulers considered a war could eliminate newly dangerous rivals, Germany to Britain oversea, Russia to Austria, Germany to France, Britain to Germany...

TL;DR: From 1815 to 1914, European politics were dominated by a handful of Great powers who ruled the continent informally in a complex equilibrum, where rivalries between them were kept to a reasonable level thanks to them having their domination to lose and little more to gain in a war; UK was just the most powerful of them and mostly played by the rules, making it unappealing to attack it.