George,

O'Donnell say of "Don't go down the mine dad"

Some speculate that the song was inspired by the great 1907 mining disaster at St Genaed in South Wales which claimed more than 100 lives.

Could he be referring to this (many more than 100)

1913: (14 October) The Explosion at Senghenydd
At the Lancaster Pit, owned by the Universal Colliery in Senghenydd, near Caerphilly, an explosion killed 439 men. The Welsh-speaking community was totally devastated by the tragedy; laid bare and stripped of a generation of its workers, many of whom were young boys. A contemporary poem reads: "
The collier's wife had four tall sons
Brought from the pit's mouth dead,
And crushed from foot to head;
When others brought her husband home,
Had five dead bodies in her room."
The coal owners had ignored warnings of the dangers in the mine only a short time before.

From Britannica online

Wassil! V