I think I've posted it here or somewhere, but it seems there were A&D approved satellite stations where the permission use number was applied.

Interesting find there Martin and it may be that the term dipped to 14 years but it seems that from the stained glass patent of John of Utynam, the intent to prevent the prescriptive use of "something" has held steady at a 20 year interval, http://www.ipo.gov.uk/p-history.htm , but then again I'm not a patent attorney.

Kind Regards,

Raimey
rse