I am told that the answer is yes, but..........
Nats has a very expensive infrastructure, in that when they bid for an airport contract, its to take over and run the entire package, usually ATC and ATC engineering.
When they put a bid in at our place, their price included not only the cost of ATCOs/ATCAs & Engineers, but also an ATC Manager and an Admin Officer. On top of that, NATS expected the airport company to pay for all rates, electricity, water and other utilities.
Serco also put a bid in, but we weren't privy to the detail.
But more sigificantly, NATS included a provision to centralise our approach radar (eventually at either Swanick or Aberdeen). Their premise being that the airport company wouldn't have to pay for the upkeep of the radar at the airport. Clever trick that one, because 5 years down the line, when the contract is up for renewal, we have no radar and NATS have us by the short and curlies.
The only real advantage NATS could provide against all others was continuity of ATCOs in the event of retirements/people leaving etc.
I suspect that this is what swung it for them at Bristol, although there was much negotiation between bean counters before the contract was signed, and even now we don't know if NATS have taken it on at a loss with the expectation of eventual profit.
My (sic) airport company decided to keep ATC in - house, much cheaper in the long run.