Thanks for posting the link wrt the London prices
I have three observations for you
1) The price list specifies that these are the average prices per metre "based on a 120 sq. m. apartment". As such, these are not average prices for the market. These are average prices for 120sq m apartments in those markets.
2) They don't identify the sources. To gather this sort of data is VERY difficult. Even more difficult is to gather this sort of data on a credible and consistent basis.
3) I did a 30 second google search on "london uk average house price", and the second hit on the list quoted avg prices for the greater london area last June at 260k GBP. At 1.7 CAD=1 GBP, this equals $450k CAD. This compares with approx $400k last June for Toronto avg. Certainly a far cry from the link you posted which suggests prices in London are 5x Toronto prices.
http://news.bbc.co.uk/2/shared/spl/hi/in_depth/uk_house_prices/counties/html/county37.stm
WRT to Toronto's population projections, I did a similarly quick google search on "toronto population projections" and the first link projected a 50% increase by 2031. I think it is high, and unlikely, but not unreasonable for a claim of doubling in 20-30 years from a different source.
http://www.toronto.ca/torontoplan/flashforward.htm