While in Europe he traveled from Switzerland to Lyon to meet with fellow Siamese student, Khuang Aphaiwong.

[3] The first official meeting of Khana Ratsadon was held at rental no.9, Rue Du Sommerard on 5 February 1927, Prayoon's 30th birthday.

In the military, he founded the Volunteer Defense Corps (VDC) and ascended to the rank of lieutenant general.

Prayoon's eldest daughter Yaowapa Pamornmontri married to Sombud Tuchinda with five children.

Prayoon Pamornmontri died on 12 August 1982, aged 85, in a crash on a Bangkok city bus at Ratchaprasong Intersection.