Following a thread on SPF, someone was querying this helicopter as it appeared in the background of the Tiger helicopter. I could see it was a Cobra but the 4-blades through me off. It took a while, but I managed to find an image of the aircraft and what it was, which was the Model 249. Web search of that revealed it was serial number 70-16019, also called a YAH-1S. I found quite a few photos of it and also that it appeared at the 1980 Farnborough Airshow. I also found it was demonstrated to the RAF.
First photo below is what started my search, and then the next one that is really revealing in details. However, the canopy shape in the first pic seems to show curved glass --- so now not sure what it is.
Now I have found I have all the parts to make a model of it in the second photo. I'll just have to make some decals for it.