Dan Hamilton writes in ConservativeHome that the Ministry of Justice in the UK has not yet directed the lectoral Commission to allocate the new seat to the UK due to it under the Lisbon Treaty rules: http://alturl.com/7vzo
Notwithstanding the conclusion he makes that this somehow shows the Labour Government has threatened British interest by not yet naming the 73rd MEP, Hamilton does make a good case for decision sooner rather than later.
It looks like the UK's 73rd seat would go to the West Midlands which would mean the Conservatives would get another MEP. Perhaps this is why there is no rush to make the nomination. If the extra seat goes to London, then Labour would get the extra MEP - Anne fairweather.
In any case, the new MEP - Tory or Labour would have to wait until 2011 (by which time a complex legal protocol will be ratified by national governments) before they are able to cast a vote as a full Member.