Kamiso is right in the 1990's it was all a bit iffy.
For a long time now all big purchases now go to Regional level then out to tender . Often more than one hospital will add into the tender.
Senior professional staff as in our Dept, assess the products, all brands short list at least x2, fores and against. All have to match our criteria.
Our recommendation is then put out to tender for best price.
Last time we did this we got £250k off the bill. The large companies want to keep us on board.
I was told once, the UK is a loss leader due to the NHS, same product cost more in Europe.