The GCAA will issue the MPL license at the end of training & successfully fulfilling the ICAO requirements by each cadet (pass tests & fly required sectors).
As far as I know, the GCAA started researching the MPL with ICAO in 2007 & had recognised it in late 2008, & will start issueing it to those cadets who went for the MPL training with a certified school such as Alpha.
AAA could have started a little earlier, but it waited for the blessings & acceptance from the GCAA, which is a must before offering such a program