Hawthorn or Birch?

I am going to guess that this is a Hawthorn shieldbug, but I could be wrong as it also looks very like a Birch shieldbug. This blip is definitely worth looking at large.

This is the first time I've seen one of these so I had to do a bit of scouting around on the net to try and see what it was. I am convinced it is a shieldbug and I think it is the Hawthorn shieldbug, but I am only using pictures to guess at what type it is so I could be wrong.

Luckily for me I was heading out this afternoon when I jumped into the car and saw this insect sitting right in front of me on the outside of the windscreen. I crept back out of the car and rushed back indoors to get my camera. I was sure it would have disappeared by the time I got back, but fortunately it hadn't budged while I was away. I managed to get quite a few photos before I had to set off in the car, but I think the fact that it was sitting on the glass, (which provided a reflection) was a great bit of good fortune.

Its Latin name is Acanthosoma haemorrhoidale. The larvae occur May-October, and feed mainly on hawthorn berries, although a range of other deciduous trees are also used, including oak, hazel and birch. While it is common and widespread in mixed woodlands across Britain and Ireland, it is somewhat scarcer in Scotland.