Renowned artist Nathan Wyburn commissioned by Mastercard    Today, a closely guarded secret has been revealed! Nathan Wyburn, the acclaimed Cardiff-based artist, has been commissioned by Mastercard to create his most ambitious work of art ever.  The former Britain’s Got Talent finalist needs help from the public and has issued a call for anyone in Cardiff this weekend to join him at the Capitol Centre from 8am – 5pm to contribute to this new piece.  Exact details of the work of art…