It can't be the stone pine, which has two needles. Also, the stone pine has very distinctive juvenile foliage, with soft short, grey needles, whereas the photo shows young vivid green needles. See also
http://en.wikipedia.org/wiki/Stone_Pine Next: the radiata does not produce candles like most 2 needle pines do, but makes shoots with short needles that gradually grow longer, and the photos here remind me of that way of growth. The places where the bark shows red may be spots where chunks of bark, large or small, were broken off. Underneath the bark is reddish.
BTW, the Scots pine is also a 2 needle pine.
I'll stick with the P. radiata. And yes, they dig quite OK and aren't difficult to grow. All the same, they are not at all my favourite pine for bonsai. I've got 3, if anyone comes to Canberra, he/she is welcome to have them for free.
Maybe it's of interest that I also had stone pines for a few years. That juvenile foliage really interferes with the growing of bonsai and I chucked them out.
Lisa