well I never

make no wonder no one has seen one before!

I will get the head unit out later this week and have a good look (well a  lot bloody better than I have already  )

I do hope it is as simple as this

thanks for your input I will report back soon

thanks to the keen eyes of langers2k we now have this sorted and have the FM now working on the head unit

it was half of the plug that was left in place when the head unit was removed.

 

I have to say in my defence that I sent the picture to 3 cable suppliers on ebay and 2 cable suppliers from a google search and the 3 ebay sellers said they couldn't help as they had never seen such a plug and couldn't help and the 2 uk suppliers never even responded so im glad I came on here

 

thanks to all who replied