300mbps 4G in the UK
300mbps 4G is readily available on EE in the UK if you can find a quiet mast in an urban location: https://twitter.com/PedroClarke1/status/853930150299398144 The maximum theoretical speed for that service is over 400mbps but the site being center of a city means it's rarely all that quiet. I regularly observe speeds of over 200mbps on Vodafone too. These are all obtained using 2x2 MIMO and 64QAM so with new devices able to better use what's deployed, the available speeds will improve even further, leading us to at least one network in the UK being able to do gigabit class 4G.
The Opensignal report does not break down the 4G results by operator which is sad considering one of the UK's networks really lets the side down