1947 Special Delivery First Day Issue

Here is another cover from my collection. A special delivery issue which is also an interesting cover from the usual ones. I got this again from Mr. Coolpit.

Here it is:

I've got closer details as well:

And again, I've only managed to scan one side of the envelope, thus another picture taken from the front side:

This part included a stamp depicting Dr. Jose Rizal(Philippines National Hero), although I'm not certain why it is in that part, instead of the other side.

Perhaps other explanations might be available somehow.