Just managed to fix it! If you can shake out the small clip from the bottom of the arm rest you are half way there. They push fit from the inside. I fed a small but stout piece of wire through the hole for the clip and out the bottom of the arm rest. Put a small 90 degree bend on the end and feed it through the hole in the clip to secure it. (Make sure you feed it on the right way round! Then use the wire to pull the clip up into the hole. Twist 90 degrees to release the clip. Only problem is you have to hold the handle in place and put the clip in place. So I had to drill few a small holes in the hand end to be able to pull the clip into place straight on with the handle in situ.
all now sorted with a tiny hole under the handle to show for it.
frustrating, awkward, difficult, but not impossible!
safe to say I won’t be using the internal handle again just in case! But at least it’s back in place properly!