I do agree to some extent, but when you look at the sovereign wealth fund that Norway has that still generates huge amounts of revenue and then look at what the UK has left... it does seem like the word "squander" is appropriate.
As a UK citizen I'm not sure that's such a good thing for the average Brit.
The rise of the City was more to do with loosened regulations, privatization and the leveraging of historical factors like trade links and banking presence globally than anything else AFAIK