: I have reverted to the pre-edit war text (i.e. "It is the world's leading financial centre alongside New York and has the fifth-largest city GDP in the world (and the largest in Europe).") 
 : This is a wording which is factually accurate and had been stable for some time. To state that London is the most 'economically powerful' city is a real stretch when its total economic output is well under half that of either Tokyo or New York. 'World's leading commercial centre' is very vague - what does commercial mean in this context?