To me, this isn’t so much an issue of socialism, but of capitalism. It’s no more than supply and demand, only rather than goods, the commodity is labor. What we are living through is a gradual leveling of labor costs across the world. It’s going to happen, the only question is at what speed.
You're right, it's largely a labour market issue. In the medium term, contrary to the general assumption, it's the skilled rather than the unskilled labour market in Britain which will be most affected. Take, for example, the position of almost any British plumbing contractor at the moment. Does he take on an unskilled teenage apprentice, and train him up for four or five years before he's qualified to work unsupervised and the employer begins to get a return on his investment? Or does he buy "off the shelf", and at far lower cost, a highly skilled, fully qualified and highly motivated Polish plumber? Extrapolate this to all skilled trades over a decade or so, and it's not hard to see the pattern which would emerge.