Certainly back in 1971 I had 1 hour on Ex. 19 , and I don't think it's changed .
Actually its changed 3 times since then!
Firstly, the 1 hour became 4 hours sometime in the 80s
In July 1999 we adopted JAR-FCL where the 4 hours diisappeard and became Ex 19 as required
We and [ we understand the CAA ] require a minimum of 1 hour for Ex.19
In April 2014 we changed to EU regulation, the CAA no longer have any say in the matter, and it remained at Ex 19 as required to comply with the EU syllabus.