If Agroforestry don't know, the Edinburgh Bot. Gardens may have mature
specimens you can eyeball (and it's an excuse to visit a great place).


Alternatively, Dawyck Botanical gardens in Peebles have a special
collection of Pinus. 24 species and 147 different plants apparently.
http://www.plantnetwork.org/directory/dawyck.htm
I'm sure someone there would know and they also may have mature
specimens you can eyeball (and it's an excuse to visit another great
place).