Rare bricks found among the debris at Pudu Jail demolition site

Site visited on the 23rd Jun 2010 , 6 a.m. , morning.

This brick was found among the debris which carry the name "KIEN HIN". What or who is "KIEN HIN" ?

Again, site re-visited on the 27th Jun 2010, 7.30a.m., morning.

  

Who or what are these two P.W.D. and Y.Y.C., do they belonged to the brick manufacturer ?

Strange is , only few pieces carried these names, almost 99.9% of the debris (bricks) with plain surface without any name.