phew! - thanks for clearing that up 
Yes, existing iPhone 5's only support LTE in the UK at 1800mhz, which means EE today and Three in future.
The EU "standard" frequencies for European LTE are 800mhz and 2600mhz - so I'm guessing a future iPhone 5S will support these.
For apple all these LTE frequencies are a pain as they can no longer have one worldwide model as they had with the 4S - but two models for USA, and at least 2 models for the rest of the world. Roaming LTE will be quite hard.
(I read there are more then 42 bands of LTE rolling out worldwide, compared to 5 bands for 3G/UMTS).
James BT Infinity 2 19/09/2012 - Estimate 44.6/6.5 - Install 52/12 - Actual 46 / 8 Mbps
Huawei VDSL -> Draytek router -> Apple Airport Extreme -> Belkin Switch -> Windows/Mac/Linux/NAS/Phone
13 years of broadband - 1999 ntl:(512k/1M)/BTbusiness(2M)/Metronet(2M)/Bulldog(8M/16M)/BE(19M/16M)/BT FTTC(46M)