As you probably know already, the strap is actually made from a synthetic material called Corfam manufactured by DuPont and dating from the late 60's, early 70's.
The one pictured is the correct strap for an Heuer Monaco of that period :-)
Best bit is the all original Heuer buckle too with the correct 'Sun' stamp on the back.
A very rare find these days.
If you want to see a really tatty old Corfam, look here!