I want to stress to Microsoft support that UK Xbox One users have a higher latency than normal.This is because the worldwide Xbox One speedtest server is based half way across the world over in Seattle, USA.
A simple test called 'Detailed Network Statistics' is performed by going into Settings, Network, Test Multiplayer Connection then waiting until 'checking connectio'n is finished. When 'Everything Is good' is displayed press All the bumper and trigger buttons together (LB,RB,LT,RT) to display the detailed network statistic settings.
Please post your results as mine is set out below :
D/Load - 58.55Mbps
U/Load - 18.35Mbps
D/Load Packetloss - 0%
U/Load Packetlosd - 0%
MTU - 1480
Latency - 149ms
With hope, we may see Microsoft change the test server to a closer speedtest server.