Qualcomm was pushing its MediaFlo wireless broadcast technology at the time and was going to use this spectrum to deliver MediaFlo services to the UK. Unfortunately that required handset vendors to license the tech and install it in their handsets, which didn't happen. It did get some traction in the US, but people rapidly lost interest. Soon after Qualcomm closed it's Media FLO division and Europe had gone the way of DVB-H (Digital Video Broadcast - Handset) anyway.
Qualcomm looked to be sitting on a bit of a spectrum white-elefant and probably wished they hadn't bothered and the who Media FLO thing and their spectrum would just go away.
Move to the present and it seems Qualcomm have just sold their 1452-1492 MHz (40MHz) spectrum to Vodafone and Three for a rumoured £100m. Nice little profit of £92m (maybe enough to cover all the Media FLO tech they gave up on).
The L-Band spectrum can be used for both supplemental download links and supplemental upload links (SDL and SUL respectively) which are part of 4G and allow operators to add extra capacity to mobile terminals (i.e. phones). Unfortunately very few if any current phones support SDL services let alone the L-Band frequencies. As phones use more and more bandwidth maybe this will change in the future.
Where the operators can use this, is for more bandwidth to basestations and it may be an easy way to boost network capacity.
As this spectrum was offered many years ago, though it was technology neutral, it wasn't covered by spectrum trading agreements and officially the spectrum trade has to be agreed by Ofcom., which may bring a slight spanner into the works. There should be no reason why Ofcom won't allow the transfer, however the annual license fees on this spectrum were calculated on the sell price (i.e. £8m). The mobile networks are charged rather more on their aggregate spectrum, so there's likely to be a hike on the spectrum fees.
Time will tell if it was a sensible purchase or not (though Qualcomm are probably now laughing while they head to the bank).