The capitol of England and the United Kingdom has no official coat of arms or flag. Now I know some readers are thinking something like "yes it does" and probably think it is these:
This video does a good job of explaining, despite its misuse of the word "crest":
The governing body of Greater London is called the London Assembly, this governs the whole city and also has some limited powers in the City of London. Each of the districts in Greater London known as boroughs (some like Westminster even have the title of city) have a local council too. In fact by UK standards Greater London is more like a province or region, (hence the term assembly rather than council)rather than a city, a quick Google comparison the population figure with London (a city) and Northern Ireland (a province) NI's population is about 1.8 million compared to Greater London's 8.1 million.
So Greater London a UK city has a larger population than a UK country.
Some of the boroughs even have their own flag and arms, for example Westminster:
All of this emphasises that Greater London needs its own emblem. In fact that used to be the case.
Greater London was originally the County of London, and had a county council its coat of arms were:
The use of the mural cornet or crown while not unheard of is relatively uncommon in the UK. In 1965 the County Council was replaced by Greater London Council (combining the individual boroughs into one city), although it was dissolved by 1986, its coat of arms was this:
The flag was a banner of arms. However in 2000 the Greater London Authority (Office of the Mayor of London and London Assembly). was established, however it was never granted a coat of arms or flag. So I had ago:
My first idea for a flag was based on the previous flag, it feature the waves and lion (although in a different colour), from previous arms. It also features the Portcullis of Westminster normally associated with Parliament. While Westminster is only a small part of Greater London it has some of the most important national buildings there, and the portcullis is also used on Greater London symbols like the coat of arms and logo of the Metropolitan Police Service:
And the badge of the London Regiment of the Army Reserve, which covers both The City of London, and Greater London:
My next design features the two roses of England, and English lion along with the Portcullis and cross of St George:
Or alternatively without St George's Cross:
This flag is really a banner of my coat of arms proposal:
The supporters feature two lions with flag staffs representing London's position as capitol of England (St George's Cross) and the capitol of the United Kingdom (Union Flag) as a whole.
The crest features a mural cornet (taken from the original County coat of arms) and two fish representing steadfastness as well as economy and science.
I hope you found this interesting and useful. If any place in the UK needs a flag and/or coat of arms it is Greater London.