Facilities at Gordonstoun School in northeast Scotland include a climbing wall, rifle range and a five-hole golf course, while pupils can even avail themselves of bagpipe lessons.But there is another reason why the institution in the far north of Scotland is well-known: one of its former pupils happens to be King Charles III.It is hard to get more isolated than Gordonstoun, which lies near the city of Elgin, on the North Sea coast some 66 miles …