You can only just make out the contours of Big Ben from the offices of The Independent on the 18th floor of Canary Wharf. The Post Office Tower, and much of the distant London skyline, appears to be covered with low cloud. On a clear day you can see Canary Wharf from almost 30 miles away, but not today.
If there were no dust, smoke, or water droplets in the air, we would be able to see about 150 miles. But there is always something to scatter the light rays and spoil the view. You need to be far from a town, and served by clean, polar maritime wind for the best visibility, and even then it's best to leave it until mid-afternoon, when the early morning mist has had a chance to clear.
Overall, though, the figures show that visibility in London is generally good. From 1982-1991, there was an average of less than one morning a year when the London Weather Centre reported visibility below 200 metres (though there were three a year at Heathrow), and an average 26 mornings a year when you could see more than 40km from the London Weather Centre. For the best view, however, you should go to Wick - 125 days a year when you can see more than 25 miles.
How pleasant to have a job when I can stare out of the window and pretend it's work.