I know how the tendering process works, and in many cases it's silly even if it's well intentioned. (Off topic) My parents have a company that has to put out contracts to tender throughout the EU, even for tiny contracts. They get tenders from foreign businesses that make no obvious attempt to win, and probably don't even know what they're actually tendering for. They're equivalents of Serco and the like, so if they did win by some fluke, they'd find out what to do and how many staff they'd need then (in reality, they'd probably sub-let it to one of the other contractors that bid on their own!). It's hard to believe that a company from the other end of the EU would come over to run a maintenance contract on a handful of properties dotted around the UK, but apply they do.
What I meant was a requirement that a company must build them here, even if a foreign company was to win the actual contract. It's a bit different for something big like a fleet of trains.