Where Wren's churches went, and which you can still walk into
Three pieces of Wren's City churches now stand somewhere else: a spire top 8.8 km away in Sydenham, a tower 18.4 km away in Twickenham, and a whole...
Akhilesh Koul, Data scientist · London
13 posts · latest 9 Oct 2026
I write about open data, mostly London, and build tools to understand it.
Latest · Part 2 of 2 · The London Underground
Is a step-free station enough?
A station label covers only part of a journey. TfL's platform records and lift notices show what changes when the route to the train breaks.
10 stationshad one or more lift records in TfL's 9 October snapshot
Recent writing
All writing →Wren's City churches: thirty years to rebuild, two centuries of losses
Of the 45 City churches rebuilt from scratch after the Great Fire, 30 were started in the 1670s, and the 19 I could verify took a median of...
Who can get to a parkrun? London's 5k map
About 4.7 million of London's 8.8 million people live within 2 km, in a straight line, of one of its 65 Saturday 5k parkruns. Central London was the...
Which parkrun came first, and can you run the alphabet?
In the 10 London parkruns I could date, event IDs follow launch order. 29 of the 65 have one-word names, Stockley Country is 6.2 km from its nearest...
Lab experiments
Explore the Lab →
A game
When did we get here?
Follow our species out of Africa on Buckminster Fuller's world map, and guess when people first reached eight places.
With the parkrun posts
Drop a parkrun
Start a new event anywhere in London and count who it brings within 2 km.
With the Tube post
Your station's day
Tube flow for any station, through a typical day.
From the blue plaques series
Voronoi playground
London's blue plaques, and what no clustering looks like.