Looks like the full budget might be closer to 1B GBP:
http://www.pulsetoday.co.uk/your-practice/practice-topics/it...
Is this not enough provide infrastructure to keep maybe 200K PCs up to date? (I don't have number on how many PCs they have...).
I'm not saying it is, or isn't. But I would be useful to explore the issue. Throwing more money at the problem isn't necessarily the solution.
IMHO, the main cost is replacing the old window support guys by linux support guys because people a rarely competent in both and erasing the windows way of thinking is very difficult. The new team has to learn the specific needs and manner of NHS. Once they have the same experience as the previous team, the cost should melt.
When you deploy an os over something as large as the NHS, your going to hit a few snags, perhaps at the code level. You will need somebody who you can phone up, who will then go bug fix those issues.
Vendors like redhat have support licences that support this. And those licences are still fairly expensive.
If NHS was going to deploy a Linux Distribution, they will have to bring a Linux distribution vender onboard which would take the role Microsoft does now.