Night-shining Clouds

Otherwise known as noctilucent clouds. These appear during June and July, high level ice crystals forming around meteor dust, volcanic dust, pollutants and water vapour. They are illuminated when the Sun is well below the horizon but it's light catches the 55 miles high clouds against darkish skies giving a wispy and ethereal appearance.
Generally they appear between 60 - 90 minutes after sunset or before sunrise. These were seen from about 2.30am until 3.30am.