The interesting thing about this question is that last (ending prefixes) of upgraded Journey series & the first prefixes of the Frontier polymer series have both the PM & current governor of the Bank of Canada. I believe that to have both a PM & acting governor on a Canadian note may be a first. And it gets interesting because for Macklem Carney (M-C) notes:
* for the Upgraded CDN Journey only 3 denominations have the signature combo ($5.00, $20.00 & $50.00)
* Upgraded $5.00 were actively culled so that all 7 prefixes HAE - HAL are tough & still sought after
* 2004 M-C $20 had just 10 prefixes & both the first AUT & last BID were short releases
* 2004 M-C $50 had just 3 prefixes AHN, AHP & AHR with both first & last short ranges reported.
+ 2013 Frontier polymer, the HBG Macklem Carney $5.00 release was delayed by over a year. A few were spotted initially & it was assumed they would be rare but then a huge amount were released out west & they trickled into regular circulation. It was tough to get them UNC. The rest of the denominations had more regular releases but the last Macklem Carney FTH $10, BSW $20, AMK $50 & EKZ $100 all have become exceptionally difficult to attain (with the M-C signature).