@mono, DGPS is now commonly used as GLS. Standard Equipment on Boeings for the last eight years or so. But not certified for low vis yet, just normal CAT I (and LTS CAT I). Certification for low vis is in progress though. I flew a few test runs for that in germany and GLS is both more stable, "smoother" and quite a bit more precise than ILS. Autolands work like a charm, same as rollout guidance of course (B737).
The problem with allocating a new frequency band for an industry, that is based worldwide and not only within the UK, is that the use of that frequency band can not be guaranteed outside the UK. So there is simply no business case to exchange current NAV radios for new ones that could use that band if the use is only possible within one country in the world. In central europe for example that FM radio band will be in use for the next 30 to 50 years, although some of it will be used by digital radio services.