Quoting from Jackonicko (via Lima Julet): It was laid down that no unnecessary expense should be incurred in making the change and where alterations in existing designs would involve such expense they should be deferred. It was stressed that Her Majesty had no objection to two different designs of the crown (i.e. the existing design and the new design) being used concurrently.
When I joined BRNC Dartmouth in September 1973 we were issued with new stock battledress adorned with "King's" buttons. I still have it in a box, although I swear it has shrunk in storage!