He was given his life peerage for his role as Blair's (not New Labour's) chief fundraiser.
His elevation in September 1997 came 4 months after Blair's election victory. Pre-General Election, Levy ran the Labour Leader's Office Fund (a blind trust established to finance Blair's work in opposition) that enabled Blair to run the biggest opposition leader's office in history. Although figures remain confidential, the best guess is that in just three years the Labour leader received around �2.5m in this manner before becoming Prime Minister. This type of arrangement is now banned under the Political Parties, Elections and Referendums Act 2000.
http://www.whatnextjournal.co.uk/Pages/Back/Wn ext25/Osler.html
His established financial acumen led to the enobled Levy to take on the role as New Labour's chief fundraiser.