All political parties are coalitions; people bound together all with slightly different worldviews, but whose ideals are similar enough that they can stand beneath the same banner. That’s true of Labour, the Conservatives, the Lib Dems, and UKIP (witness the tension between the “little Englanders” and new defectee Douglas Carswell).
So the joint administration which has run Southend since the start of June is a coalition twice over; a coalition of three coalitions. That it has held together even this long is a surprise to some, but on the part of Labour and the Lib Dems that has to be down to party ties and the clear ideals for which they stand (and, in the case of the Lib Dems, oblivion if they do, oblivion if they don’t).
It says a lot, then, that the most fractious element of the joint administration is the one lacking those party ties — which, actually, is something they wear as a perverse badge of honour. If the joint administration does fall apart, then I am convinced it will be because of the Independent element.