In the days of mass-produced British cars, much of the brightwork was in fact, chrome-plated MAZAK. The metal is an easy one to cast, especially in die casting, it follows the form correctly and many thousands can be churned out per day. But as it is a mixture, or more correctly an alloy of, zinc, copper and aluminium with the majority percentage being cheap zinc, it soon rots. It has a low melting point.
Chrome is itself porous so salt and water gets underneath it and causes the zinc to corrode. You see this as little pimples which after about five years explode into a white dust. But as far as the motor industry was concerned, it had served its purpose. It is impossible to re-chrome MAZAK and is an American invention being called ZAMAK over there. So, sixty years or more later, you, like me are probably looking at replacing the worst bits of chrome on your Y Type.
By far the most expensive in terms of size to replace, are the bonnet catches. Up until now you would have to have found someone to cast you new ones, and then get them polished and plated. But NTG now sell their own versions and it was for a set of four I plunged. They are easy to swap over, but the new ones have a different thread on their studs as well as a bigger head to the nut.
Do run some oil down inside them to lubricate the spring and the ‘hook end’; do this before you fit them. Removing the old ones is straight forward but you will need to save the gasket they have between the bonnet side and the cast body. The photos show the old corroded ones, the new shiny ones, and the gasket required.