Hi, I wonder if anyone can shed any light on this?

I have a signed copy of the 1990 paperback 'Watching' by Jim Hitchmough that my mother bought at one of his book signings in 1994. Just out of curiosity I searched on Ebay and there is a copy for sale for £69.21p. Not quite believing this I googled the title and there are a few copies out there, prices up to £185! 

Is this for real? Would anyone know why they might be expected to fetch this kind of price (unsigned)? It seems extraordinary...

Thanks in advance.