Mark1,
Thanks for the reply. The reason i'm asking is regarding historic Auster aircraft, some i've seen have C of A's and other are on a Permit to fly, which got the cogs turning as i couldn't distguish why they could be different? So out of the two, which would be the most stringent set of rules, and if looking towards purchasing an aircraft which would be better to have, the C of A or Permit, or doesn’t matter.......
I apologise if these are all straight forward bone questions but i'm a complete novice on the Engineering side of aviation.
Rus