The Royal College of Arms Version (1935)
These are the Arms and Motto as recorded by the Royal College of Arms in 1935.
The castle and the key are different from the ones in the Royal Warrant of 1502 granted by King Ferdinand and Queen Isabel.
Though it is not a very popular version, it is sometimes used locally on cheap, mass-produced flags.
Notice that there is no gold border on the Arms since this would have placed gold (yellow) beside silver (white) and this was contrary to the rules of the Royal College of Arms.