Your right on the money there Phil, pardon the pun.
The last 20 years of my 37 working years in the construction trade was estimating cost of works and whenever we put forward costing for anything within 10 miles from London city centre we would add at least 30% to 50% to the figure that our computers would compute so a £250,000 would be £400,000 to £500,000.
We never wanted work in London anyway, if we could help it, as its just too much trouble but believe it or not we still use to win jobs there so had plenty of money in the pocket for any chargers they throw at us but you can see another reason why London is made so expensive to live there.
That said, the centre of most cities are getting this way no matter where and I’ve always use to make a joke about parking charges, congestion charges and the cost of a gallon all comes out in the cost of a loaf of bread.?