Brussels - Things are rarely simple in the EU's complex bureaucracy, but the procedure for choosing new host cities for two London-based regulatory agencies after Brexit is one of its most fiendish inventions yet.
European affairs ministers will decide the new locations of the European Medical Agency (EMA) and the European Banking Authority (EBA) in a secret ballot on Monday after months of campaigning by candidate cities.
The 27 member states -- without Britain -- will vote in several rounds using a points system that has been compared to a less glamorous version of the Eurovision Song Contest finals.
It promises to be bitterly fought contest.
"I fear we are going to have to order in sandwiches," a European source said, predicting a vote that would stretch into Monday night.
- Mutual backscratching -
The ministers will decide on the medical agency first, for which 23 cities have put forward their names, followed by the banking regulator, for which there are eight candidates.
Some cities have applied for both, and if one of those scoops the EMA, it will have to withdraw its candidacy for the other.
For the vote, each state will have six points to award: three for its first choice, two for the second choice, and one for the third -- much like the Eurovision competition although without the famous 'nul points' option.
With much tactical voting and mutual backscratching likely to be involved, the vote will be sensitive, so ballots will be secret and the number of votes for each city will not be revealed.
Map of the cities bidding to host the European Medicines Agency and the European Banking Authority
If a city is the first choice of at least 14 countries -- a majority of the 27 EU states -- it will be named the new host of that agency outright.
If not, there will be a second round of voting, but this time with each member state having only one point to award, to its first choice. Again, the winner must get 14 votes.
Should there still be no clear winner then there will be a third and final round -- a run off between the two candidate cities with the most votes, although in theory there could be more than two if some cities are tied.
Again, the runoff vote will be with one vote per country.
In case there is a tie at the end of this third round, the winner will be decided by a draw.
One reason that the vote may take a long time is that there will be breaks between each round.
"The ministers can contact their capitals to get advice on how to vote for the next round," a diplomatic source said.