What might be causing clicking in my extension lead ?

[PokerP]

My 4 plug, 2 usb, surge protected extension lead started producing a clicking noise about 2 months after purchase.
The clicks are every ~0.4 seconds and start as soon as the power is supplied to the extension lead, even when nothing else in the room is plugged in to anything.
The clicks sound like they are coming from behind the usb sockets.
They are only just audible, about the same as a quiet 'British tut'.
After the power is disconnected, the clicks continue for ~150 seconds but gradually slow down until ~3 seconds frequency.
Obviously I stopped using it as soon as they started, but what might be causing it and can the unit be fixed?

 

[DPG]

Sounds like it may be something in the switch mode power supply supplying the USB sockets, but difficult to say.

If it didn't do it for the 1st couple of months, and it does it when nothing is plugged in, then I would take it back to be on the safe side.

A 'British tut' - if that's not an SI unit then it should be!

 

[Wilko]

A 'British tut' - if that's not an SI unit then it should be!

Agreed !
BTU - British Tut Unit