I have just discovered that the front section of the body on my '81 just at the point of the bonnet "V" (and either side of it) seems to be seperating from the metal rail which runs beneath it. Where I am talking about is the section of the body immediately behind the headlights up to the bonnet a few inches away. This section has a metal rail beneath it which I expect it should sit flush on top of, but in my case is seperating and lifting to leave about a quarter inch gap between them at the point of the "V", reducing from there out both sides.

The consequence of this is (1) The "V" of the body is now noticeably above the matching "V" of the bonnet, and (2) the headlights are catching on the body panel at the back edge of the headlight units when they raise, and have now chipped paint off the edges of the body panel where they catch

Help !! Thoughts and fixes needed please      

The headlight support bar you reference is bonded to the hood surround panel.  You should be able to rebond yours with some SMC compatible bonding compound.

You will almost certainly need to completely remove it and clean up the old, failed bonding material.  It is easier if you remove the hood first.  Then use big clamps well padded to hold it in place for a few hours.  Cover the underside with wax paper to avoid any problems.

Thanx for the info, can you shed any more light on what an SMC bonding compund is please