There is a small arm or link between the two hinges on my front drivers side door which when the door is fully opened locks into place to stop the door flying back at me if Im parked facing uphill.

It has suddenly stopped working but still has the small locking-pin in place where it joins the cars actual body.

Im guessing it's come loose inside the door?

Yes, that's the check-strap and its pin. I have lots of fun with them. Best to remove the door card and see if anything's lose or missing inside.

Thanks; does it connect to a pin inside the door?

Things always seem to go wrong with my car when its really cold weather...

The check strap bolts to the inside of the door frame.

Its probably rusted away knowing my luck!

The bolts can just work loose. Should not have rusted as the check strap should be lubricated with mentanace

I removed the door card this morning to discover that the mechanism that stops the door from slamming back on you when you're facing uphill has broken off. It's an offset "S-shaped" bar that has snapped completely in half, it was sitting in the bottom of the door frame!

I have removed the passenger side mechanism and put it on the drivers side which obviously gets more use. Im eventually gonna replace the passengers side if I can find another check-strap mechanism from a scrapyard????