Your comments contain fundamental errors.
I won't go into great detail, why Three failed to acquire 4G spectrum and how it was subsequently awarded significantly valuable frequency from EE in the process. However, there is a lot more to how Three (Broadband) came to acquire frequency in the 3.4─3.8GHz spectrum. There was no auction neither were there any wars. It was via the acquisition of UK Broadband & Relish, which was already a part of PCCW. It was originally awarded the spectrum, contingent upon certain stipulations ie. building, maintaining and continued investment in telecoms infrastructure.
The current 5G product might bear the moniker, but it is still using the infrastructure put in place by UKBG Relish in parts of Central & Greater London. The speeds are also dependent upon relevant upgrades to the masts, operator equipment, backhaul etc., more importantly the UE has to be up-to-date to take advantage of any speed boosts. It will still not count as real 5G for sometime yet, as there are standards which are still being ratified and other players have yet to join the game.
It would be naive to assume that Vodafone, the biggest operator by spectrum holdings, followed by BT/EE, will just defer their incumbent position, without bidding next year!
https://www.ispreview.co.uk/index.php/2019/08/three-uk-aim-f...
https://www.capacitymedia.com/articles/3659839/Three-UK-agre...