BBC on Centre Ground.

"Although the voters were moving leftwards, the Labour Party was seen as even further left, and it was not until 1997, when Tony Blair had abandoned the extremes of left-wing Labour policy and moved his party to the centre, that they won."

""Most voters are in the centre-ground. Most party members and most MPs are not," Dr Tom Quinn, one of John Bartle's colleagues at Essex University, told BBC Radio 4's World at One.
"When you see parties which track closely to the centre-ground like Blair's New Labour, it causes internal tensions. So there were always problems between Blair and the trade unions, and Blair and the Brown-ites. When David Cameron moved the Conservatives to the centre it caused problems with the Conservative right.
http://www.bbc.co.uk/news/uk-politics-31973051