Make some reasearch based on the websites below and find the nicknames and specificities for each element.
The London Black Cabs
https://en.wikipedia.org/wiki/Hackney_carriage
The Phone Booth
http://www.thephoneybox.com/history.html
The Queen's Guards
http://projectbritain.com/royal/guard.htm
The British Flag
http://www.know-britain.com/general/union_jack.html
The Clock of Westminster Parliament
http://factsforkids.net/big-ben-facts-kids-exciting-8-facts-clock-tower/
Red Buses