...it's the word "Octothorpe" for the # symbol.
One call queuing system I phone regularly says "please enter your user ID followed by the pound key".
Since when did # look like £
That's because they haven't translated it properly from US English. In the usa # is known as the pound symbol as it was used instead of lb when referring to weights eg 12# instead of 12lb. So no connection with pound as in £ sterling.
i always assumed it was because it looked vaguely like a
square equilateral field with 4 walls - a pound, as in a compound.
But for me it's a sharp sign.