English Greenery?

I've spent a good portion of the last 20 years living in the second largest country in the world with a population hovering around 35 million. For that reason it was somewhat of a drastic change to move to a country smaller than most of Canada's provinces fitting nearly double that population. Despite this fact England is still able to boast a relatively impressive amount of greenery- mostly outside of London. Living in the capital, however, there isn't much opportunity for genuine fresh air. This is slowly turning into my main complaint about being here and why I take many opportunities to seek greener pastures elsewhere. So far Epping Forest, Hyde, and Valentine Park are the parts of London I've been able to breathe a little better. I suppose there are some things Canadians do take for granted and that is the amount of national parks at their disposal. Hopefully England works a little harder to maintain its greenery instead of focusing on a seemingly endless influx of people.