French Handcuffs from Portugal

I received a pair of French Darby handcuffs from a dealer in Portugal with the original key.  They are much lighter and smaller than the usual Hiatt.  There are no markings and the end caps are plain and about 18mm in diameter.  Checking my reference material, I could not find and information or see another key like this one.  They are very well made despite the surface condition.  

Checking the history of Portugal,  they were invaded by the Spanish and the French in the early 1800's.  Maybe that is how they got to Portugal.

Ron

And I thought I did well by purchasing a Lips ball Darby. Congratulations on your find sir. Ron J

Take away the key head and I'd say English, second half of 1800s.
With plain end caps I'd say the bolts and key are not original, ie repaired. 

A repair doesn't account for no peining marks. If the end caps had stamping to hold the end it, then they would still be there after a repair (as any darby modified for escape work would attest) Probably just never stamped. I'd say these are English, the key is a replacement.

Here is a better picture of one of the end caps.  I did find a stamp on one of the cuffs in the area below the hinge.  I could be a size number but it is unreadable.

Ron

Thanks Ron. The decay of the metal gives me the impression they have been in contact with soil (at least on one cuff)

The last picture I posted of the end cap is in much better condition than the other one.  The springs are quite weak so I thought they may have been gimmicked.  I was able to rap both sides open.  Maybe this set belonged to an escape artist.  Who knows?

Ron

The last pic does not show the plug within the flange, so cannot see any peining.

I think the puzzle is solved.  I agree they are British and the key is a replacement.  They did come out of Portugal and most likely belonged to an escape artist.  They are rappers which explains the end cap replacement in able to get to the springs.

Ron

Thanks Ron for the update and extra info.