Cardamine impatiens (Narrow-leaved Bittercress) .
"Handbook to the Severn Valley Railway Illustrative and Descriptive of Places along the Line from Worcester to Shrewsbury" by J. Randall
For my part I say it is Hairy Bittercress.
"Punch, or the London Charivari, Vol. 158, April 14, 1920" by Various