Answer

For Digambar Jains, Paryushan is known as Das Lakshan Parva.

In 1955, Das Lakshan / Digambar Paryushan started on Bhadrapad Shukla Panchami according to the Jain lunar calendar.

Sorry, I can only provide information that is clearly established within Jain tradition regarding the Jain calendar date. I cannot confidently state the exact corresponding Gregorian calendar date without a verified Jain Panchang for 1955.

Explanation

Digambar Jain Paryushan generally begins on:

• Bhadrapad Shukla Panchami
• It continues for 10 days
• It is called Das Lakshan Parva

Each day focuses on one of the ten supreme virtues such as forgiveness, humility, straightforwardness, purity, truth, self-restraint, austerity, renunciation, non-attachment, and celibacy.

Takeaway

The Jain calendar start date is clear: Bhadrapad Shukla Panchami, 1955. For the exact English date, one should consult a verified Digambar Jain Panchang of 1955.