The history of cut thumbs, is however hard to find a good source on.

I have also had problems documenting this allegation. I first read of it in a summary of British Colonialism in India by an Economics Masters student with whom I was collaborating in an interdisciplinary study in 1964-5. I will inquire of him. Perhaps he recalls the source he found. Have to have a source before it can be evaluated. :-)

"It is not necessary to have hope in order to persevere."