Thanksgiving cactus ( Schlumbergera truncata )

The leaf shape suggests to me this is what is known, at least across the pond as a Thanksgiving cactus.  This is for the obvious reason that it flowers around the time of Thanksgiving.  I think this one is actually a "Haven't got a calendar cactus.  It throws flowers periodically in ones and twos right throughout winter round 'til Easter.

The points on the leaves suggest Schlumbergera.  Christmas cacti are Schlumbergera bridgesii and they have notches rather than points.  Easter cacti are Rhipsalidopsis gaertneri, it has only very slight indents in the leaf which is more eliptical than the others.