Is this the stair light?
Also, question should clarify whether these are flickering when the power is ON, or OFF.
Assuming OFF, it's because of stray power on the circuit, usually from electrostatic coupling from other cables (though degraded insulation is also a possibility).
I've even seen a CFL flicker on a (UK, 230V) dual switched circuit (stair light) though CFL are much less prone to it.
In this circuit there's an upstairs switch, and a downstairs switch, both SPCO (changeover) switches, and a 2-core cable (+earth) between them. In this arrangement, the lamp is ON when both switches connect to the same core, and OFF when one switch connects to the other core.
This leaves power connected to the "off" core via the capacitance between the cores for the whole length of the cable, and you can see half the supply voltage via several hundred pF, capable of sourcing tens of microamps. (Why only half? There's a similar capacitance to that Earth line).
That's enough to slowly charge up the capacitor in a LED bulb (and rarely in a CFL) until it turns on momentarily, drains the cap, off again, and repeat.
Other circuits may exhibit this to an extent, but it's particularly bad in stair lights for the above reason.
If this is what you're seeing, it's worth having the wiring checked for degraded insulation, but otherwise it's a curiosity rather than a problem. Any incandescent bulb, however low power, on that circuit, will drain the stray power before it becomes a problem.