We have a peculiar situation where NHS can't raise wages, but they certainly can hire staff from agencies at much higher rates (and agency mark up). Imagine if NHS could hire staff directly at those rates...
Leaving aside the political aims of the governing party, the NHS employs a lot of people, it's the biggest employer in Europe and one of the biggest in the world, so even a 1% raise costs a large sum of money.
Large nominal sums of money are really easy to turn into a negative headline, rather than the cost of using staffing agencies which requires a bit of analysis.
See Brexit for an example. "We're spending £350m per week on this, isn't that mad?!" versus "various analyses and projections show that raising trade barriers and reducing staff mobility will likely have a negative effect on domestic businesses"
The Conservative party wishes to destroy (by privatization) the National Health System. It will be replaced with a "health" system substantially identical to the American system.
NHS management is notoriously corrupt and a bureaucratic nightmare, which is why the national health service failed in the UK.
If you live elsewhere and are surprised to have never heard about this, it’s because it hasn’t been acknowledged yet by the government to save face, but anyone with relatives stuck on a NHS waiting list or who have sadly passed away waiting for an ambulance that doesn’t come already knows this.