Hi Craig / Tony
Tony's description of the pick up hitch sounds similar to mine. The hook meets the bottom plate of the pin hitch. If I remove a horizontal pin, this allows the pin drawbar to pull out / extend. It also then drops when you lower the pick-up hitch. It always looks to me that someone has adapted it from something else.
I will take some pictures on Friday when I get home. I am in Amersham at the moment.
Home is Wylye, where the A303 and A36 cross. My U1000 also came from Mudie Bond before they stopped selling them. Was great driving it home...
Cheers
John