What would this have been used for?

[Tengu]

needs a new loop, this is a hook with a clip.

 

[Asa Samuel]

Hanging pots over fires maybe?

 

[Matt.S]

Some sort of animal harness?

 

[falling rain]

Horsey type bridle tack? type thing.

 

[hog]

One in each ankle for hanging up meat?

 

[gsfgaz]

hanging up ropes

 

[launditch1]

Could be off an old horse drawn plough trace.

Ive also seen similar hooks on well chains,designed so the bucket doesnt fall off when its dropped into the water.

I cant lay my hands on the book that has a pic right now

 

[Sainty]

Looks like a wrought iron karribiner?

Martin

 

[launditch1]

Spring billet.

Just found the book on old chain making.