What could be the possible advantages of the insularity of Great Britain? Please give a citation for your answer because I need to cite my answers.

One advantage of the insularity of Great Britain is that is has been hard to attack Great Britain. The island location creates many logistical problems for a potential invader. Germany tried to invade Great Britain in World War II and failed. Napoleon talked about an invasion, but that never occurred. Being surrounded by water requires an amphibious invasion. This is more difficult to achieve. Thus, one advantage of being insular is that is has helped keep Britain independent.
Another advantage of British insularity is that it has helped Great Britain develop a culture that is unique to Great Britain. The British are known for being reserved. They have been able to absorb different groups of people into Great Britain. However, they still have been able to maintain a uniquely British perspective as well as their own culture. This has allowed Great Britain to remain fiercely independent, and not necessarily be so tied to activities in Europe. The recent Brexit vote is an example of this independence from European activities and influences.
https://www.telegraph.co.uk/culture/tvandradio/9505711/The-British-how-insularity-and-the-weather-shaped-our-national-identity.html