What might an el cheapo micro USB to HDMI cable be useful for?

Paid my pound at Poundland and bought the said cable only to read later that a MHL/Slimport adapter is actually the thing to use. I've done the obvious and plugged the cable into the TV then my phone (also tablet, in case) but nothing happened in spite of my fiddling with the TV settings.

Is this a pound down the drain or has this lead an hdmi- related use, please?