As previously explained by Planetizen, Prince Charles has courted controversy by weighing in on architectural commissions and decisions throughout the country, and his position gives him what many call an unfair vote in these decisions. As Robert Booth of The Guardian reports, the Prince is also asked as a matter of routine to approve of legislation "...in what is effectively a power of veto."
Booth reports that much of the Prince's power comes from his position as the Duke of Cornwall. All decisions that might effect the crown of the Duchy must go to the Prince for a possible veto. Cornwall, as Booth says, is "no backwater," including the entire town of Poundbury.