Understand
While looking through the Electoral Commisions website I found some voter and non-voter satisfaction statistics that show some pretty interesting things.
I also found some stats on overall participation.
I also found
Turnout of eligible voters in % across the years [Full article]
Turnout of eligible voters from the 'General Elections 1853-2011 - Dates and Turnouts' pdf on the Electoral Commision website [Link]
As is visible from this information voter turnout in general is still decreasing with less and less newly eligible voters voting each election. It looks like rather than not wanting to vote the reason most non-voters don't vote is for pretty small reasons; couldn't make it, forgot, etc. This shows the lack of importance placed on the system, this could be either because people don't fully understand it or don't believe in it, either way the system needs to change and until it does voting is becoming less and less relevant.