Re: @DavCrav
Yes, low paid workers were forced into these schemes by their employers. On top of this, senior legal professionals advised that they were legitimate and legal, so many of those who weren't forced into them thought that they were a safe and legal way to minimise their tax burden.
In fact, AFAIK, they WERE legal at the time. Whether they were moral or ethical is another matter, but if something was legal when it was done it should not retrospectively changed. What if the government decided that the national speed limit on motorways should be changed to 50mph, and every motorist who had done more than that over the last 10+ years should be done for speeding?
So, the main points here should be that:
a) Those who were forced onto these schemes with no understanding should not be targeted, and
b) Laws should not be made retrospective, they should apply only from the point they come into force.