2.3m in the UK watched a live stream of the ENG vs. WAL game at Euro 2016

"BBC Online attracted record breaking digital figures for the home nations Euro 2016 clash between England and Wales on June 16th with 2.3 million unique browsers watching online, more than double the previous record, while a peak audience of 9.3 million million people (73 per cent share) tuned in on BBC One.
An all-time high audience of 14.6 million unique global browsers visited the BBC Sport website on the day to follow coverage of Euro 2016, including Northern Ireland’s match against Ukraine. This breaks the previous record of 13.6 million browsers set on the final day of the 2015-16 Premier League season."
Source:  Advanced Television, 17th June 2016