Written answer in the House of Commons, 11 Dec 2006 : Column 771W
Mr. MacShane: To ask the Secretary of State for Foreign and Commonwealth Affairs what legal opinion she has obtained on the size of the European Commission after 2009. 
Mr. Hoon: The legal position on the size of the European Commission after 2009 is clear. The provisions are set out in the Protocol on enlargementof the European Union adopted at Nice. The Protocol requires that following the accession of the 27th member state, the number of Commissioners shall, from the date on which the first Commission takes up its duties (i.e. 2009), be less than the number of member states.
Quotebank comment: this means that at least some treaty reforms are needed – a defeat for the “policy delivery only” school of thought