Re-roofing the barn.

For some time I haven't been entirely happy with the roof covering on the barn.
The later efforts of applying individual slates/tiles looks so much better.
However, I was concerned that trying to add individual slates would destroy the roof thus giving me yet more work to do.
Looking for something or other in the loft the other day, I came across a pad bought in Majorca a few years ago. Whilst of only about 70gsm paper, it did have 4mm squares printed on it- result!
Each square is cut up to the next line and is pared off in 8mm strips and adhered with a 4mm overlap. The first five courses are shown- this is a really quick way of tiling a roof- why didn't I think of it earlier? I am sure I saw it somewhere before.