I remember the first time this happened. We had an exchange RCAF instructor at nav school in 1969. He went home on a Friday night as a flight lieutenant in a blue uniform and reappeared on the Monday as a captain in a funny green one!
I see the article says the change was actually in 1968 - maybe the news was slow to get through!
Fascinating article here on proposed RAF commissioned ranks when the service was first formed in 1918:
http://www.rafweb.org/Ranks1.htm
TTN (flight leader retd.)