Turnout is lowest amongst urban, ethnic, young and disadvantaged voters and these disenfranchised voters are much more likely to vote Labour. If we truly are a party that wants to help the disadvantaged then we will honour our referendum pledge on PR. Here are the facts;
General Election Turnout (2005) (Power Report).
Labour lead over Tories (2001) (Urban Renaissance).
18-24 14% Labour lead over Tories
65+ 1% Tory lead over Labour
Non-White 61% Labour lead
White 9% Labour lead
D/E 31% Labour lead
A/B 9% Tory lead
It's quite clear from this (despite 2001 being latest figures I could find for the second bit), that the party that would benefit the most from improving registration and turnout would be the Labour party.
Not only would it be a boost to democracy by re-enfranchising these 'lost millions' of voters, it would benefit the Labour party electorally. Not only that, the addition of these voters would also enable the Labour party to move to the left.
For more on this, see my article on how PR will help alleviate poverty.
And see how turnout has risen in New Zealand since they moved from a Westminster system to PR. This rise in turnout has been most sharp amongst the young, ethnic, and lower socio-economic background voters. The Labour government has just won a third term under PR and has increased it's vote at each election, over and above the rise in turnout.
As the Power Commission correctly pointed out, electoral reform is only part of the answer (along with more devolved power, less concentration of media ownership and reformed party funding), but it is an important part.
Even the Tory vice chairman of the Power Report, Ferdinand Mount came round to PR;
"People may still be deterred from voting if they feel that their vote does not make any difference, which in safe seats it doesn't. (Nothing was more off-putting at the 2005 general election than the spectacle of Conservative and Labour strategists boasting that they needed only to canvass the 2% of voters in marginal seats who were going to make the difference and whose names they had locked away in their "voter vaults".) The only answer is to introduce some form of responsive electoral system in which every vote cast goes towards helping a candidate to get elected. I have spouted all the arguments against proportional representation myself in the past. David Cameron and Ken Clarke are spouting them still. But I have been converted to reform, not so much because it is fairer than first-past-the-post but because it is the only way to galvanise the parties to canvass every ward in every seat."