All of the other Mobile Network Operators (MNOs) didn't want EE to be able to do this, but Ofcom have decided that it's in the public interest for them to do so, even though it may give EE a short-term competitive advantage. O2 have published their disappointment in this result.
EE currently have 2 x 60 MHz bands in 1800MHz though under the agreement with the competition commission they have to divest 2 x 15 MHz as part of its merger (leaving them with 2 x 45 MHz). Ofcom have allowed EE to utilise LTE on the full bands, not just the bands that EE will retain after the digital divide auctions expected next year (Ofcom will auction the 800MHz and 2.6GHz bands and EE's spectrum will become available as part of this).
It is rumoured that devices such as the iPhone 5 will be able to use LTE services in this band, so EE will be the only UK operator that allows full use of the iPhone's data capabilities.
Ofcom has also published a statement on the interference of LTE in the 800MHz bands which could affect TV services in the future, though their testing has shown that actual interference should be minimal for real use scenarios.
Ofcom's full statement is here.