You can't just pluck trained medical staff out of thin air though.
Even in hospitals they are using non ICU specialist nurses because there aren't enough specialist nurses to go round and they're having to treat 3 patients per nurse when it's usually one on one.
The underfunding chickens are coming home to roost unfortunately.
When the Nightingale Hospitals were built all local hospitals were instructed to send a proportion of their staff off to be trained to work in them when they became functional. No one extra was employed to staff them (as far as I am aware) so hospitals lost staff while they went off and got trained, and then had to prepare for the loss of the same staff when they became operational.
The problem is not building new hospitals, or temporary facilities to look after patients, it's staffing them, and that is due to many factors already identified on this thread. One of the biggest problems with regards to recruitment into the NHS is that it is no longer seen as an attractive career option, long hours, authoritarian management, poor pay (relative to the hard work it takes to train), poor work conditions, a blame culture that pervades throughout the NHS to name just a few of the issues.
All too often the people who work in the NHS are exploited by the management of the hospitals, and their selfless nature taken advantage of by way of 'guilt tripping' them into accepting things that they really should not have to.
No wonder the NHS is loosing staff hand over fist.