History repeats itself. There have been men tunnelling under London until just a few weeks ago to create the new Crossrail routes with 21 km of new tunnels. They have had the benefits of modern tunnelling machines which the men in the stamp card above did not.
These men were creating the first underground electric railway, using a Greathead Shield. They had to dig out the clay from behind the the shield then force the shield forward. The original image for the stamp card above came from the London Transport Museum and you can see it on the Transport for London site.
The stamps and stamp cards were issued in 2013 to commemorate 150 years of the London Underground. I did show this card just over two years ago.
This is a post for Sunday Stamps, in its current home at "See it on a Postcard!"