pow whats it stand for ?

I have been given a chunky silver ring, The hallmark i tiny but I can just makeout the lion then two other symbols that i cannot make out, and befor all that are POW anyone know what POW stands for on a silver ring??? is it a maker, I might have to ask a friendly jeweller to read the hallmark for me, It has a lovely unusual stone in it too. It looks like a gents ring that he would wear on his little finger, but am just guessing. Any help on the POW would be great.

Best Regards