A signature alone on a painting unfortunately does not prove in which period the artwork was painted...
I purchased a Tongdee thai movie poster painting from "Never Say Never Again" in 2004 and thought for years that it was the original one from 1983. then I found out that the seller (a certain Atchara Putong aka Benz) cheated me. They "customs created" the painting for me in 2004 and sold it to me as vintage 1983..
Brilliant fake nevertheless