Check out this article in the Telegraph (of all papers) which is about a UK Government report that
"An average trade union member earns £4,000-a-year more than non-unionised workers". Now this is in part due to more professionals joining trade unions but the research also showed that there has been a decade of better pay deals for union members compared to non union employees.
The UK is an unequal country and for a long time more money has gone to senior management and less in wages. While minimum and living wages are important the only way to reverse this trend is for strong, independent trade unions to freely bargain with employers to get fairer pay for workers. Quite simple really. The more of us in the union the better the deal we will get.
I hope that readers enjoy my favourite YouTube clip of all time. (or this clip or this clip)