 Complete the following phrase:  Gibraltars first sovereignty referendum is celebrated annually on Gibraltar National Day 10 September. It is a public holiday, during which most Gibraltarians dress in their national colours of red and white. Until 2016, the tradition had been to also release 30,000 similarly coloured balloons, which represented the people of Gibraltar. However, this tradition has now been ended because of the threat that it poses to wildlife, particularly marine. The 300th anniversary of 