Warning: seems to be unusuable because (check) Spain and UK had reservations on Gibraltar right from the beginning 
One published instance of a political agreement being cancelled is the company takeover bids directive (Official Journal C 1996: 162/5), 'one of the most contentious dossiers to be dealt with in the EU in recent years'. 'June 1999: Political agreement on common position on Council (not adopted due to disagreement between UK and Spain over the territorial application to Gibraltar)'
Source: The European Political Space: Measuring Preferences of Actors in European Union Decision Making by Robert Thomson (Department of Public Administration, Univ Leiden), Jovanka Boerefijn and Frans Stokman (Rijkuniversiteit Groningen).
Working paper 2001-32 of ECPR Standing group on analytical politics and public choice http://www.oprit.rug.nl/stokman/artikel/ThomsonEPS.pdf http://athena.leidenuniv.nl/fsw/bestuurskunde/onderzoek/ecpr/content_docs/working_papers/thomson.doc
also as: European Journal of Political Research Vol 43 (2004) 237-261 Actor alignments in European Union decision making
http://articles.findarticles.com/p/articles/mi_m0WXI/is_1999_Dec_11/ai_58249003
