lot of this stuff with the letter is noise. When the tories were in power they were doing the same thing Labour will be doing, haggling on price.
Both parties will have a number in mind for what they are prepared to pay. Any subsidies negotiations will take months regardless. This notion that Universal will throw a strop and walk away are fantasy, either the board approved the money or it didn't. It wouldn't be a very good business decision on NBCU part if the entire costings of the project were contingent on getting a full discount from UK PLC. Ask yourself how much discount on a multi billion project youd be willing to accept before you just had to get on with it all, cos you know youll make it back with ROI eventually?