Watching an old episode of QI Stephen Fry states that it is common for a barrel of beer to be buried in the cement under the stoop or steps leading up to the door of a house (Youtube clip here).
First of all, is this true? If it is true why was it done?
I would doubt it. Having something degradable and/or decomposable in cement is going to weaken the structure (this is why the urban legend of there being a bunch of dead bodies of workers in the Hoover Dam is implausible). Additionally, who pours enough cement to bury an entire barrel?
WAG: it’s like the butcher putting his thumb on the scale. Putting a large hollow vessel in the middle of a big pour of concrete vastly decreases the amount of concrete they have to actually use, but (presuming they got away with it) not the amount they charged for.
If there was no need to make the stoop a solid block of concrete, an empty barrel would have been a cheap and easily accessible way to add a hollow space.