OK, so the peanuts/monkeys comment was a bit of a cheap shot. I apologise.
However, the ATCOs at Luton, Cardiff and Belfast are probably very pleased with their current salaries. Now obviously the cost of supplying an aerodrome service is far from solely dependent on ATCO salaries, but it is something that any alternative supplier would have to strongly consider.
So TBI offers the contract to someone else. For argument's sake, we'll call them "Orces". This is what the ATCOs will be thinking:
1) Will I be expected to take a pay cut?
2) Will the nice pension fund I've been building up for XX years be affected?
If the answer to either of these questions is yes, and let's face it, it could well be, then Orces are going to have trouble convincing many of the ATCOs to stay.
The resulting ATCO shortage could be devastating for a couple of years until Orces can validate new recruits. The financial damage could be worse than keeping NATS as the supplier.
And yes indeed, TBI probably knew what they were getting into. In a materialistic world, it's easy to offer people more for doing the same job than to try and convince them to take less. I dare say if NATS walked into Red Dragon's ATCU tomorrow and said, "We're running this operation now, your new salary will be £#####", then he'd graciously accept.