New Spanish Slate v Original Delabole Cornish Slate

Unfortunately when you re-roof a house it is reckoned that you are likely to lose about 1/3 of the original slates due to damage.  So we had to find an alternative slate that matched the colour and texture.  My builder reccommended Spanish slates.  I did some research and went to look at some houses he had built to see what they looked like (a)  as new, just recently fitted  and  (b) after being on the roof for a couple of years and 'weathered' .  I was happy with how they looked and agreed that we would use the new slate on the far end of the master bedroom and the 'turret' which is the part of the roof above the grand staircase and the  kitchen with Stanley's big chimney.

This was the state of the roof before :

You can see where the slates have slipped, and the holes in the roof.

This is the same section now:

This is the newly roofed section, using Spanish slate and hung rather than nailed in place