This column is a monument dedicated to the Duke of York. Obviously not the current Duke; after The! Scandal! nobody is going to create a statue to Prince "No Sweat" Andrew.
Instead, it is dedicated to the second son of King George III, Prince Frederick. He was born in 1763 and died in 1827 at the age of 63. Since he was the spare rather than the heir, he went into the army to make a living. He didn't have an auspicious start and wasn't particularly effective in his first command. However after he gained some experience he became a very good commander; not so much in the field but in relation to organisation and logistics, two things that an army can't fight without.
The monument was constructed in 1834, seven years after his death.