JFTDWS
+++ Out of Cheese Error +++
Perhaps indeed, Anglebracket. That particular eta was in reference to wagtail's statement that of course less weight = faster /higher etc 
Our native ponies wouldn't have evolved if they hadn't been up to work and weight.
Has anyone ever seen a highland pony carry a stag off a hill?
According to wikipedia... the typical stag of scotland is a red deer and an adult weighs 30st plus.
A 15st stag is tiny in comparison isn't it?
BigBen... you there hun? We've found a great pony for you!