Rod, I did a quick search to see whether you had created a specific anti-theft marking thread, but couldn't find one. Decided then to slot this one in here.
Not prevention of theft of the stamps, this time, but of the contents. Maybe the servant was given the money and the envelope to take to the post office, where the stamps were attached.

Jaipur State, SG 9 and 11a - dated 27 June '7(0?) - which would work out to about 1913
In case you were wondering why they didn't put the stamps on the
front of the cover ...

The large scrawl at the top left on the front of the cover is actually another, and far more powerful, anti-theft device, the number '74'. The explanation is rather lengthy, but Rod at least, may find it interesting to read through ...
From Frits Staal's
The Stamps of Jammu & Kashmir, pp124-125:
'Envelopes even more than single stamps are often marked with scribbles, lines, dots, or other symbols that are supposed to prevent them from being taken away or opened by unauthorized outsiders. A similar practice adopted by Hindus in Jammu and Kashmir, Indore, Jaipur, and so on is to write: //74// at the beginning of the address to insure safe delivery of the letter. ... Professor Bruce Pray has drawn my attention to a story translated from the Hindi in
Linguistic Survey of India, vol. VI, pp48-49 about the miraculous powers of song. The singer Tan-sen sang with such force that all the lamps at the court of Emperor Akbar lit themselves, and Tan-sen himself burst into flames and fell down dead. Earlier, he had warned that if such a thing would happen, he could be brought to life only by Queen Kamla of Chittaur. The Emperor therefore attacked Chittaur and a terrible battle ensued. Seventy-four and a half maunds (one maund being equal to approximately 80 lbs.) of sacred threads were collected from the corpses of the slain. Queen Kamla was taken prisoner, and when ordered to sing, she sang with such force that her soul burst its way through her skull and went to heaven, leaving the audience with their mouths open in astonishment. The number 74˝ is still written on letters as the strongest of seals, for "the sin of the slaughter of Chittaur" is thereby incurred by all who violate the letter.'