The Sony Xperia 5 III is now available in the UK and with WH-H910N headphones as a pre-order bonus. Unfortunately, the smartphone is only available through EE, O2 and Vodafone with expensive contracts.
https://www.notebookcheck.net/Sony-Xperia-5-III-launches-in-the-UK-exclusive-to-mobile-networks-with-WH-H910N-headphones-as-a-pre-order-bonus.568477.0.html