I was just reading an article by journalist Norman Lewis about a visit to Bangkok in the 1950's where he attended a party held by Kukrit Prajov, then a newspaper editor and later prime minister.
At the party Lewis criticised Kukrit for admiting he'd never eaten Thai food his chef being western trained. So later Kukrit managed to get an invitation for dinner for himself and Lewis off another guest who had a Thai chef.
The guest who invited them was a prince and grandson of King Chulalongkorn. He lived in a large mansion on the edge of Bangkok.
Kukrit and Lewis arrived for dinner and were given a tour of his house. In one room Lewis saw a strange bird-like cage hanging and ask what it was. The prince replied "uncle lives there". Lewis inquired "you mean like a spirit house?" The prince elaborated uncle was the former head servant, helped raise the children and was happy to sacrifice himself for the family.
Lewis obviously rather shocked got the prince to explain, he told the full story. When a new royal house was finished it was traditional to strike a bargain with a man of low caste. He would sacrifice his remaining years in return for acceptance into the royal family and would be entitiled to equal ritual offerings in exchange for becoming the guardian spirit of the family. The prince said he didn't witness the sacrifice himself because he was a child but he said a large religeous ceremony was held at the time.