Three UK is on a bit of a roll.

– USA one of four new fear-free roaming destinations for Three customers.
– Three customers can use their UK data, text and calling allowance while in the USA, Indonesia, Sri Lanka and Macau.
– Feel At Home now operates in 11 destinations around the world.

– In the UK , Three has started rolling out 4G speeds in London, Birmingham and Manchester.
– This is for a selection of customers in these areas initially just to make sure there are no issues

I use Three UK and find it it be an excellent operator when it comes to tariff allowances and pricing.