They live in a very interesting Universe. Just compare real data and this BS.
2008 = 16 200, not 13 800
2009 = 17 300, not 11 300 (Polish GDP have never decreased during last 20 years!)
2010 = 17 800, not 12 300
2011 = 18 800, not 13 400
2012 = 20 100
2011 = 35 100
2012 = 35 900
20 100 / 35 900 = ~2/3 (it looks a little different than "five times")
I wouldn't afraid Romanians and Bulgarians in England so much.
At first, there are much smaller countries than Poland (even together they are smaller).
Second, Poles had many family relationships and they were soaked in Anglo-Saxon culture, especially in the time (and against) Russian occupation. They used to learn English language intensively, read newspapers, watch movies. May be that people weren't plumbers or carpenters looking just for better job conditions, but I am convinced that such orientation used to share all groups more or less. Bulgarians are more like Greek or Serbian orientated and Romanians are closer to French culture. Much less sinister.