Review the House of Lords voting record of Lord Mandelson.
Members may not vote in every division of the House. This can be due to a number of reasons; for example the Lord Speaker, Senior Deputy Speaker and Principal Deputy Chairman of Committees do not vote because of the impartiality of their positions. Otherwise, a Member could be absent undertaking other parliamentary business or unable to attend for other reasons. There is no procedure for recording intentional abstentions but a member may be present in the House and choose not to vote.
To perform a more comprehensive search of vote/division results, use the House of Lords votes in Parliament pages.