Going to be doing this again this year with the fakes.
They worked perfectly for me and my Dad (ten miles up the road) last year.
Could say I was cabbage white/caterpillar egg laying free on all my sprouts.
A few gardens down, speaking with a neighbour, said last year was a bad year for the cabbage white/caterpillar , not as bad as 2012 which we agreed was the worst for many years. His are semi covered too, so they tried hard.
At least I know it wasn't a poor year for them.