As scheduled, the UK price of the OnePlus 3 went up by £20. It now stands at £329, to compensate for the drop in the exchange rates of the British pound. The price in mainland Europe hasn't budged, it's still 400. Countries not using the euro (Sweden, Denmark, Poland, Czech Republic, Hungary), haven't seen a price hike either. OnePlus is working at razor-thin margins to offer flagship specs below the price of mainstream competitors, so unfavorable exchange rates can quickly hurt the company. Source
Source: http://www.gsmarena.com/uk_price_of_oneplus_3_goes_up_to__pound330_after_pound_drops_in_value-news-19319.php